Using super in C

Question

My style of coding includes the following idiom   class Derived   public Base      public         typedef Base super     note that it could be hidden in                              protected private section  instead           Etc        This enables me to use  super  as an alias to Base  for example  in constructors   Derived int i  int j       super i   J j        Or even when calling the method from the base class inside its overridden version   void Derived  foo        super  foo                And then  do something else     It can even be chained  I have still to find the use for that  though    class DerivedDerived   public Derived      public         typedef Derived super     note that it could be hidden in                                 protected private section  instead           Etc       void DerivedDerived  bar        super  bar        will call Derived  bar    super  super  bar      will call Base  bar            And then  do something else     Anyway  I find the use of  typedef super  very useful  for example  when Base is either verbose and or templated   The fact is that super is implemented in Java  as well as in C   where it is called  base   unless I m wrong   But C   lacks this keyword   So  my questions    is this use of typedef super common rare never seen in the code you work with  is this use of typedef super Ok  i e  do you see strong or not so strong reasons to not use it   should  super  be a good thing  should it be somewhat standardized in C    or is this use through a typedef enough already    Edit  Roddy mentionned the fact the typedef should be private  This would mean any derived class would not be able to use it without redeclaring it  But I guess it would also prevent the super  super chaining  but who s gonna cry for that     Edit 2  Now  some months after massively using  super   I wholeheartedly agree with Roddy s viewpoint   super  should be private  I would upvote his answer twice  but I guess I can t

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I ve quite often seen it used  sometimes as super t  when the base is a complex template type  boost  iterator adaptor does this  for example

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One problem with this is that if you forget to  re- define super for derived classes  then any call to super  something will compile fine but will probably not call the desired function   For example   class Base   public   virtual void foo               class Derived  public Base   public      typedef Base super      virtual void foo                 super  foo         call superclass implementation             do other stuff                       class DerivedAgain  public Derived   public      virtual void foo                    Call superclass function         super  foo          oops  calls Base  foo   rather than Derived  foo                            As pointed out by Martin York in the comments to this answer  this problem can be eliminated by making the typedef private rather than public or protected

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I ve always used  inherited  rather than super   Probably due to a Delphi background   and I always make it private  to avoid the problem when the  inherited  is erroneously omitted from a class but a subclass tries to use it   class MyClass   public MyBase   private      Prevents erroneous use by other classes    typedef MyBase inherited        My standard  code template  for creating new classes includes the typedef  so I have little opportunity to accidentally omit it   I don t think the chained  super  super  suggestion is a good idea- If you re doing that  you re probably tied in very hard to a particular hierarchy  and changing it will likely break stuff badly

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I ve seen this idiom employed in many codes and I m pretty sure I ve even seen it somewhere in Boost s libraries  However  as far as I remember the most common name is base  or Base  instead of super   This idiom is especially useful if working with template classes  As an example  consider the following class  from a real project    template  lt typename TText  typename TSpec gt  class Finder lt Index lt TText  PizzaChili lt TSpec gt   gt   PizzaChiliFinder gt        public Finder lt Index lt TText  PizzaChili lt TSpec gt   gt   Default gt        typedef Finder lt Index lt TText  PizzaChili lt TSpec gt   gt   Default gt  TBase                 Don t mind the funny names  The important point here is that the inheritance chain uses type arguments to achieve compile-time polymorphism  Unfortunately  the nesting level of these templates gets quite high  Therefore  abbreviations are crucial for readability and maintainability

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I just found an alternate workaround   I have a big problem with the typedef approach which bit me today    The typedef requires an exact copy of the class name   If someone changes the class name but doesn t change the typedef then you will run into problems    So I came up with a better solution using a very simple template   template  lt class C gt  struct MakeAlias   C        typedef C BaseAlias       So now  instead of  class Derived   public Base   private      typedef Base Super       you have  class Derived   public MakeAlias lt Base gt           Can refer to Base as BaseAlias here      In this case  BaseAlias is not private and I ve tried to guard against careless usage by selecting an type name that should alert other developers

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One additional reason to use a typedef for the superclass is when you are using complex templates in the object s inheritance   For instance   template  lt typename T  size t C  typename U gt  class A           template  lt typename T gt  class B   public A lt T 99 T gt             In class B it would be ideal to have a typedef for A otherwise you would be stuck repeating it everywhere you wanted to reference A s members   In these cases it can work with multiple inheritance too  but you wouldn t have a typedef named  super   it would be called  base A t  or something like that   --jeffk

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I ve seen this idiom employed in many codes and I m pretty sure I ve even seen it somewhere in Boost s libraries  However  as far as I remember the most common name is base  or Base  instead of super   This idiom is especially useful if working with template classes  As an example  consider the following class  from a real project    template  lt typename TText  typename TSpec gt  class Finder lt Index lt TText  PizzaChili lt TSpec gt   gt   PizzaChiliFinder gt        public Finder lt Index lt TText  PizzaChili lt TSpec gt   gt   Default gt        typedef Finder lt Index lt TText  PizzaChili lt TSpec gt   gt   Default gt  TBase                 Don t mind the funny names  The important point here is that the inheritance chain uses type arguments to achieve compile-time polymorphism  Unfortunately  the nesting level of these templates gets quite high  Therefore  abbreviations are crucial for readability and maintainability

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FWIW Microsoft has added an extension for   super in their compiler

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One problem with this is that if you forget to  re- define super for derived classes  then any call to super  something will compile fine but will probably not call the desired function   For example   class Base   public   virtual void foo               class Derived  public Base   public      typedef Base super      virtual void foo                 super  foo         call superclass implementation             do other stuff                       class DerivedAgain  public Derived   public      virtual void foo                    Call superclass function         super  foo          oops  calls Base  foo   rather than Derived  foo                            As pointed out by Martin York in the comments to this answer  this problem can be eliminated by making the typedef private rather than public or protected

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is this use of typedef super common rare never seen in the code you work with   I have never seen this particular pattern in the C   code I work with  but that doesn t mean it s not out there   is this use of typedef super Ok  i e  do you see strong or not so strong reasons to not use it    It doesn t allow for multiple inheritance  cleanly  anyway    should  super  be a good thing  should it be somewhat standardized in C    or is this use through a typedef enough already   For the above cited reason  multiple inheritance   no  The reason why you see  super  in the other languages you listed is that they only support single inheritance  so there is no confusion as to what  super  is referring to  Granted  in those languages it IS useful but it doesn t really have a place in the C   data model   Oh  and FYI  C   CLI supports this concept in the form of the    super  keyword  Please note  though  that C   CLI doesn t support multiple inheritance either

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I ve always used  inherited  rather than super   Probably due to a Delphi background   and I always make it private  to avoid the problem when the  inherited  is erroneously omitted from a class but a subclass tries to use it   class MyClass   public MyBase   private      Prevents erroneous use by other classes    typedef MyBase inherited        My standard  code template  for creating new classes includes the typedef  so I have little opportunity to accidentally omit it   I don t think the chained  super  super  suggestion is a good idea- If you re doing that  you re probably tied in very hard to a particular hierarchy  and changing it will likely break stuff badly

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One additional reason to use a typedef for the superclass is when you are using complex templates in the object s inheritance   For instance   template  lt typename T  size t C  typename U gt  class A           template  lt typename T gt  class B   public A lt T 99 T gt             In class B it would be ideal to have a typedef for A otherwise you would be stuck repeating it everywhere you wanted to reference A s members   In these cases it can work with multiple inheritance too  but you wouldn t have a typedef named  super   it would be called  base A t  or something like that   --jeffk

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I don t know whether it s rare or not  but I ve certainly done the same thing   As has been pointed out  the difficulty with making this part of the language itself is when a class makes use of multiple inheritance

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Super  or inherited  is Very Good Thing because if you need to stick another inheritance layer in between Base and Derived  you only have to change two things  1  the  class Base  foo  and 2  the typedef  If I recall correctly  the C   Standards committee was considering adding a keyword for this    until Michael Tiemann pointed out that this typedef trick works   As for multiple inheritance  since it s under programmer control you can do whatever you want   maybe super1 and super2  or whatever

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This is a method I use which uses macros instead of a typedef  I know that this is not the C   way of doing things but it can be convenient when chaining iterators together through inheritance when only the base class furthest down the hierarchy is acting upon an inherited offset   For example      some header h   define CLASS some iterator  define SUPER CLASS some const iterator  define SUPER static cast lt SUPER CLASS amp  gt   this   template lt typename T gt  class CLASS   SUPER CLASS      typedef CLASS lt T gt  class type      class type amp  operator          template lt typename T gt  typename CLASS lt T gt   class type CLASS lt T gt   operator       int       class type copy    this         Macro      SUPER         vs        Typedef       super  operator          return copy      undef CLASS  undef SUPER CLASS  undef SUPER   The generic setup I use makes it very easy to read and copy paste between the inheritance tree which have duplicate code but must be overridden because the return type has to match the current class   One could use a lower-case super to replicate the behavior seen in Java but my coding style is to use all upper-case letters for macros

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Super  or inherited  is Very Good Thing because if you need to stick another inheritance layer in between Base and Derived  you only have to change two things  1  the  class Base  foo  and 2  the typedef  If I recall correctly  the C   Standards committee was considering adding a keyword for this    until Michael Tiemann pointed out that this typedef trick works   As for multiple inheritance  since it s under programmer control you can do whatever you want   maybe super1 and super2  or whatever

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I use this from time to time  Just when I find myself typing out the base class type a couple of times  I ll replace it with a typedef similar to yours   I think it can be a good use  As you say  if your base class is a template it can save typing  Also  template classes may take arguments that act as policies for how the template should work  You re free to change the base type without having to fix up all your references to it as long as the interface of the base remains compatible   I think the use through the typedef is enough already  I can t see how it would be built into the language anyway because multiple inheritence means there can be many base classes  so you can typedef it as you see fit for the class you logically feel is the most important base class

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is this use of typedef super common rare never seen in the code you work with   I have never seen this particular pattern in the C   code I work with  but that doesn t mean it s not out there   is this use of typedef super Ok  i e  do you see strong or not so strong reasons to not use it    It doesn t allow for multiple inheritance  cleanly  anyway    should  super  be a good thing  should it be somewhat standardized in C    or is this use through a typedef enough already   For the above cited reason  multiple inheritance   no  The reason why you see  super  in the other languages you listed is that they only support single inheritance  so there is no confusion as to what  super  is referring to  Granted  in those languages it IS useful but it doesn t really have a place in the C   data model   Oh  and FYI  C   CLI supports this concept in the form of the    super  keyword  Please note  though  that C   CLI doesn t support multiple inheritance either

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is this use of typedef super common rare never seen in the code you work with   I have never seen this particular pattern in the C   code I work with  but that doesn t mean it s not out there   is this use of typedef super Ok  i e  do you see strong or not so strong reasons to not use it    It doesn t allow for multiple inheritance  cleanly  anyway    should  super  be a good thing  should it be somewhat standardized in C    or is this use through a typedef enough already   For the above cited reason  multiple inheritance   no  The reason why you see  super  in the other languages you listed is that they only support single inheritance  so there is no confusion as to what  super  is referring to  Granted  in those languages it IS useful but it doesn t really have a place in the C   data model   Oh  and FYI  C   CLI supports this concept in the form of the    super  keyword  Please note  though  that C   CLI doesn t support multiple inheritance either

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I use this from time to time  Just when I find myself typing out the base class type a couple of times  I ll replace it with a typedef similar to yours   I think it can be a good use  As you say  if your base class is a template it can save typing  Also  template classes may take arguments that act as policies for how the template should work  You re free to change the base type without having to fix up all your references to it as long as the interface of the base remains compatible   I think the use through the typedef is enough already  I can t see how it would be built into the language anyway because multiple inheritence means there can be many base classes  so you can typedef it as you see fit for the class you logically feel is the most important base class

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I don t know whether it s rare or not  but I ve certainly done the same thing   As has been pointed out  the difficulty with making this part of the language itself is when a class makes use of multiple inheritance

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Super  or inherited  is Very Good Thing because if you need to stick another inheritance layer in between Base and Derived  you only have to change two things  1  the  class Base  foo  and 2  the typedef  If I recall correctly  the C   Standards committee was considering adding a keyword for this    until Michael Tiemann pointed out that this typedef trick works   As for multiple inheritance  since it s under programmer control you can do whatever you want   maybe super1 and super2  or whatever

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Super  or inherited  is Very Good Thing because if you need to stick another inheritance layer in between Base and Derived  you only have to change two things  1  the  class Base  foo  and 2  the typedef  If I recall correctly  the C   Standards committee was considering adding a keyword for this    until Michael Tiemann pointed out that this typedef trick works   As for multiple inheritance  since it s under programmer control you can do whatever you want   maybe super1 and super2  or whatever

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I use this from time to time  Just when I find myself typing out the base class type a couple of times  I ll replace it with a typedef similar to yours   I think it can be a good use  As you say  if your base class is a template it can save typing  Also  template classes may take arguments that act as policies for how the template should work  You re free to change the base type without having to fix up all your references to it as long as the interface of the base remains compatible   I think the use through the typedef is enough already  I can t see how it would be built into the language anyway because multiple inheritence means there can be many base classes  so you can typedef it as you see fit for the class you logically feel is the most important base class

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FWIW Microsoft has added an extension for   super in their compiler

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I use the   super keyword  But it s Microsoft specific   http   msdn microsoft com en-us library 94dw1w7x aspx

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I use the   super keyword  But it s Microsoft specific   http   msdn microsoft com en-us library 94dw1w7x aspx

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Bjarne Stroustrup mentions in Design and Evolution of C   that super as a keyword was considered by the ISO C   Standards committee the first time C   was standardized   Dag Bruck proposed this extension  calling the base class  inherited    The proposal mentioned the multiple inheritance issue  and would have flagged ambiguous uses   Even Stroustrup was convinced   After discussion  Dag Bruck  yes  the same person making the proposal  wrote that the proposal was implementable  technically sound  and free of major flaws  and handled multiple inheritance   On the other hand  there wasn t enough bang for the buck  and the committee should handle a thornier problem   Michael Tiemann arrived late  and then showed that a typedef ed super would work just fine  using the same technique that was asked about in this post   So  no  this will probably never get standardized   If you don t have a copy  Design and Evolution is well worth the cover price   Used copies can be had for about  10

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I won t say much except present code with comments that demonstrates that super doesn t mean calling base   super    base   In short  what is  super  supposed to mean anyway  and then what is  base  supposed to mean    super means  calling the last implementor of a method  not base method  base means  choosing which class is default base in multiple inheritance    This 2 rules apply to in class typedefs   Consider library implementor and library user  who is super and who is base   for more info here is working code for copy paste into your IDE    include  lt iostream gt      Library defiens 4 classes in typical library class hierarchy class Abstract   public      virtual void f     0      class LibraryBase1       virtual public Abstract   public      void f   override               std  cout  lt  lt   Base1   lt  lt  std  endl            class LibraryBase2       virtual public Abstract   public      void f   override               std  cout  lt  lt   Base2   lt  lt  std  endl            class LibraryDerivate       public LibraryBase1      public LibraryBase2          base is meaningfull only for this class         this class decides who is my base in multiple inheritance private      using base   LibraryBase1   protected         this is super  base is not super but base      using super   LibraryDerivate   public      void f   override               std  cout  lt  lt   I m super not my Base   lt  lt  std  endl          std  cout  lt  lt   Calling my  default  base     lt  lt  std  endl          base  f                 Library user struct UserBase       public LibraryDerivate   protected         NOTE  If user overrides f   he must update who is super  in one class before base      using super   UserBase     this typedef is needed only so that most derived version        is called  which calls next super in hierarchy         it s not needed here  just saying how to chain  super  calls if needed         NOTE  User can t call base  base is a concept private to each class  super is not  private      using base   LibraryDerivate     example of typedefing base       struct UserDerived       public UserBase          NOTE  to typedef who is super here we would need to specify full name        when calling super method  but in this sample is it s not needed          Good super is called  example of good super is last implementor of f          example of bad super is calling base  but which base        void f   override               super  f              int main         UserDerived derived         derived calls super implementation because that s what         super  is supposed to mean  super    base     derived f            Yes it work with polymorphism      Abstract  pUser   new LibraryDerivate      pUser- gt f         Abstract  pUserBase   new UserBase      pUserBase- gt f        Another important point here is this    polymorphic call  calls downward super call  calls upwards   inside main   we use polymorphic call downards that super calls upwards  not really useful in real life  but it demonstrates the difference

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is this use of typedef super common rare never seen in the code you work with   I have never seen this particular pattern in the C   code I work with  but that doesn t mean it s not out there   is this use of typedef super Ok  i e  do you see strong or not so strong reasons to not use it    It doesn t allow for multiple inheritance  cleanly  anyway    should  super  be a good thing  should it be somewhat standardized in C    or is this use through a typedef enough already   For the above cited reason  multiple inheritance   no  The reason why you see  super  in the other languages you listed is that they only support single inheritance  so there is no confusion as to what  super  is referring to  Granted  in those languages it IS useful but it doesn t really have a place in the C   data model   Oh  and FYI  C   CLI supports this concept in the form of the    super  keyword  Please note  though  that C   CLI doesn t support multiple inheritance either

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I won t say much except present code with comments that demonstrates that super doesn t mean calling base   super    base   In short  what is  super  supposed to mean anyway  and then what is  base  supposed to mean    super means  calling the last implementor of a method  not base method  base means  choosing which class is default base in multiple inheritance    This 2 rules apply to in class typedefs   Consider library implementor and library user  who is super and who is base   for more info here is working code for copy paste into your IDE    include  lt iostream gt      Library defiens 4 classes in typical library class hierarchy class Abstract   public      virtual void f     0      class LibraryBase1       virtual public Abstract   public      void f   override               std  cout  lt  lt   Base1   lt  lt  std  endl            class LibraryBase2       virtual public Abstract   public      void f   override               std  cout  lt  lt   Base2   lt  lt  std  endl            class LibraryDerivate       public LibraryBase1      public LibraryBase2          base is meaningfull only for this class         this class decides who is my base in multiple inheritance private      using base   LibraryBase1   protected         this is super  base is not super but base      using super   LibraryDerivate   public      void f   override               std  cout  lt  lt   I m super not my Base   lt  lt  std  endl          std  cout  lt  lt   Calling my  default  base     lt  lt  std  endl          base  f                 Library user struct UserBase       public LibraryDerivate   protected         NOTE  If user overrides f   he must update who is super  in one class before base      using super   UserBase     this typedef is needed only so that most derived version        is called  which calls next super in hierarchy         it s not needed here  just saying how to chain  super  calls if needed         NOTE  User can t call base  base is a concept private to each class  super is not  private      using base   LibraryDerivate     example of typedefing base       struct UserDerived       public UserBase          NOTE  to typedef who is super here we would need to specify full name        when calling super method  but in this sample is it s not needed          Good super is called  example of good super is last implementor of f          example of bad super is calling base  but which base        void f   override               super  f              int main         UserDerived derived         derived calls super implementation because that s what         super  is supposed to mean  super    base     derived f            Yes it work with polymorphism      Abstract  pUser   new LibraryDerivate      pUser- gt f         Abstract  pUserBase   new UserBase      pUserBase- gt f        Another important point here is this    polymorphic call  calls downward super call  calls upwards   inside main   we use polymorphic call downards that super calls upwards  not really useful in real life  but it demonstrates the difference

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After migrating from Turbo Pascal to C   back in the day  I used to do this in order to have an equivalent for the Turbo Pascal  inherited  keyword  which works the same way  However  after programming in C   for a few years I stopped doing it  I found I just didn t need it very much

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I was trying to solve this exact same problem  I threw around a few ideas  such as using variadic templates and pack expansion to allow for an arbitrary number of parents  but I realized that would result in an implementation like  super0  and  super1   I trashed it because that would be barely more useful than not having it to begin with   My Solution involves a helper class PrimaryParent and is implemented as so   template lt typename BaseClass gt  class PrimaryParent   virtual public BaseClass   protected      using super   BaseClass  public      template lt typename    ArgTypes gt      PrimaryParent lt BaseClass gt  ArgTypes    args    BaseClass args           Then which ever class you want to use would be declared as such   class MyObject   public PrimaryParent lt SomeBaseClass gt    public      MyObject     PrimaryParent lt SomeBaseClass gt  SomeParams         To avoid the need to use virtual inheritance in PrimaryParenton BaseClass  a constructor taking a variable number of arguments is used to allow construction of BaseClass   The reason behind the public inheritance of BaseClass into PrimaryParent is to let MyObject have full control over over the inheritance of BaseClass despite having a helper class between them   This does mean that every class you want to have super must use the PrimaryParent helper class  and each child may only inherit from one class using PrimaryParent  hence the name    Another restriction for this method  is MyObject can inherit only one class which inherits from PrimaryParent  and that one must be inherited using PrimaryParent   Here is what I mean   class SomeOtherBase   public PrimaryParent lt Ancestor gt     class MixinClass       Good class BaseClass   public PrimaryParent lt SomeOtherBase gt   public MixinClass        Not Good  now  super  is ambiguous  class MyObject   public PrimaryParent lt BaseClass gt   public SomeOtherBase      Also Not Good   super  is again ambiguous  class MyObject   public PrimaryParent lt BaseClass gt   public PrimaryParent lt SomeOtherBase gt      Before you discard this as an option because of the seeming number of restrictions and the fact there is a middle-man class between every inheritance  these things are not bad   Multiple inheritance is a strong tool  but in most circumstances  there will be only one primary parent  and if there are other parents  they likely will be Mixin classes  or classes which don t inherit from PrimaryParent anyways   If multiple inheritance is still necessary  though many situations would benefit to use composition to define an object instead of inheritance   than just explicitly define super in that class and don t inherit from PrimaryParent   The idea of having to define super in every class is not very appealing to me  using PrimaryParent allows for super  clearly an inheritence based alias  to stay in the class definition line instead of the class body where the data should go   That might just be me though   Of course every situation is different  but consider these things i have said when deciding which option to use

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After migrating from Turbo Pascal to C   back in the day  I used to do this in order to have an equivalent for the Turbo Pascal  inherited  keyword  which works the same way  However  after programming in C   for a few years I stopped doing it  I found I just didn t need it very much

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I don t recall seeing this before  but at first glance I like it   As Ferruccio notes  it doesn t work well in the face of MI  but MI is more the exception than the rule and there s nothing that says something needs to be usable everywhere to be useful

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Bjarne Stroustrup mentions in Design and Evolution of C   that super as a keyword was considered by the ISO C   Standards committee the first time C   was standardized   Dag Bruck proposed this extension  calling the base class  inherited    The proposal mentioned the multiple inheritance issue  and would have flagged ambiguous uses   Even Stroustrup was convinced   After discussion  Dag Bruck  yes  the same person making the proposal  wrote that the proposal was implementable  technically sound  and free of major flaws  and handled multiple inheritance   On the other hand  there wasn t enough bang for the buck  and the committee should handle a thornier problem   Michael Tiemann arrived late  and then showed that a typedef ed super would work just fine  using the same technique that was asked about in this post   So  no  this will probably never get standardized   If you don t have a copy  Design and Evolution is well worth the cover price   Used copies can be had for about  10

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This is a method I use which uses macros instead of a typedef  I know that this is not the C   way of doing things but it can be convenient when chaining iterators together through inheritance when only the base class furthest down the hierarchy is acting upon an inherited offset   For example      some header h   define CLASS some iterator  define SUPER CLASS some const iterator  define SUPER static cast lt SUPER CLASS amp  gt   this   template lt typename T gt  class CLASS   SUPER CLASS      typedef CLASS lt T gt  class type      class type amp  operator          template lt typename T gt  typename CLASS lt T gt   class type CLASS lt T gt   operator       int       class type copy    this         Macro      SUPER         vs        Typedef       super  operator          return copy      undef CLASS  undef SUPER CLASS  undef SUPER   The generic setup I use makes it very easy to read and copy paste between the inheritance tree which have duplicate code but must be overridden because the return type has to match the current class   One could use a lower-case super to replicate the behavior seen in Java but my coding style is to use all upper-case letters for macros

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I ve quite often seen it used  sometimes as super t  when the base is a complex template type  boost  iterator adaptor does this  for example

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Bjarne Stroustrup mentions in Design and Evolution of C   that super as a keyword was considered by the ISO C   Standards committee the first time C   was standardized   Dag Bruck proposed this extension  calling the base class  inherited    The proposal mentioned the multiple inheritance issue  and would have flagged ambiguous uses   Even Stroustrup was convinced   After discussion  Dag Bruck  yes  the same person making the proposal  wrote that the proposal was implementable  technically sound  and free of major flaws  and handled multiple inheritance   On the other hand  there wasn t enough bang for the buck  and the committee should handle a thornier problem   Michael Tiemann arrived late  and then showed that a typedef ed super would work just fine  using the same technique that was asked about in this post   So  no  this will probably never get standardized   If you don t have a copy  Design and Evolution is well worth the cover price   Used copies can be had for about  10

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I use this from time to time  Just when I find myself typing out the base class type a couple of times  I ll replace it with a typedef similar to yours   I think it can be a good use  As you say  if your base class is a template it can save typing  Also  template classes may take arguments that act as policies for how the template should work  You re free to change the base type without having to fix up all your references to it as long as the interface of the base remains compatible   I think the use through the typedef is enough already  I can t see how it would be built into the language anyway because multiple inheritence means there can be many base classes  so you can typedef it as you see fit for the class you logically feel is the most important base class

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I ve always used  inherited  rather than super   Probably due to a Delphi background   and I always make it private  to avoid the problem when the  inherited  is erroneously omitted from a class but a subclass tries to use it   class MyClass   public MyBase   private      Prevents erroneous use by other classes    typedef MyBase inherited        My standard  code template  for creating new classes includes the typedef  so I have little opportunity to accidentally omit it   I don t think the chained  super  super  suggestion is a good idea- If you re doing that  you re probably tied in very hard to a particular hierarchy  and changing it will likely break stuff badly

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FWIW Microsoft has added an extension for   super in their compiler

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I use the   super keyword  But it s Microsoft specific   http   msdn microsoft com en-us library 94dw1w7x aspx

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I don t know whether it s rare or not  but I ve certainly done the same thing   As has been pointed out  the difficulty with making this part of the language itself is when a class makes use of multiple inheritance

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I don t recall seeing this before  but at first glance I like it   As Ferruccio notes  it doesn t work well in the face of MI  but MI is more the exception than the rule and there s nothing that says something needs to be usable everywhere to be useful

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I ve always used  inherited  rather than super   Probably due to a Delphi background   and I always make it private  to avoid the problem when the  inherited  is erroneously omitted from a class but a subclass tries to use it   class MyClass   public MyBase   private      Prevents erroneous use by other classes    typedef MyBase inherited        My standard  code template  for creating new classes includes the typedef  so I have little opportunity to accidentally omit it   I don t think the chained  super  super  suggestion is a good idea- If you re doing that  you re probably tied in very hard to a particular hierarchy  and changing it will likely break stuff badly

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I ve quite often seen it used  sometimes as super t  when the base is a complex template type  boost  iterator adaptor does this  for example

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I was trying to solve this exact same problem  I threw around a few ideas  such as using variadic templates and pack expansion to allow for an arbitrary number of parents  but I realized that would result in an implementation like  super0  and  super1   I trashed it because that would be barely more useful than not having it to begin with   My Solution involves a helper class PrimaryParent and is implemented as so   template lt typename BaseClass gt  class PrimaryParent   virtual public BaseClass   protected      using super   BaseClass  public      template lt typename    ArgTypes gt      PrimaryParent lt BaseClass gt  ArgTypes    args    BaseClass args           Then which ever class you want to use would be declared as such   class MyObject   public PrimaryParent lt SomeBaseClass gt    public      MyObject     PrimaryParent lt SomeBaseClass gt  SomeParams         To avoid the need to use virtual inheritance in PrimaryParenton BaseClass  a constructor taking a variable number of arguments is used to allow construction of BaseClass   The reason behind the public inheritance of BaseClass into PrimaryParent is to let MyObject have full control over over the inheritance of BaseClass despite having a helper class between them   This does mean that every class you want to have super must use the PrimaryParent helper class  and each child may only inherit from one class using PrimaryParent  hence the name    Another restriction for this method  is MyObject can inherit only one class which inherits from PrimaryParent  and that one must be inherited using PrimaryParent   Here is what I mean   class SomeOtherBase   public PrimaryParent lt Ancestor gt     class MixinClass       Good class BaseClass   public PrimaryParent lt SomeOtherBase gt   public MixinClass        Not Good  now  super  is ambiguous  class MyObject   public PrimaryParent lt BaseClass gt   public SomeOtherBase      Also Not Good   super  is again ambiguous  class MyObject   public PrimaryParent lt BaseClass gt   public PrimaryParent lt SomeOtherBase gt      Before you discard this as an option because of the seeming number of restrictions and the fact there is a middle-man class between every inheritance  these things are not bad   Multiple inheritance is a strong tool  but in most circumstances  there will be only one primary parent  and if there are other parents  they likely will be Mixin classes  or classes which don t inherit from PrimaryParent anyways   If multiple inheritance is still necessary  though many situations would benefit to use composition to define an object instead of inheritance   than just explicitly define super in that class and don t inherit from PrimaryParent   The idea of having to define super in every class is not very appealing to me  using PrimaryParent allows for super  clearly an inheritence based alias  to stay in the class definition line instead of the class body where the data should go   That might just be me though   Of course every situation is different  but consider these things i have said when deciding which option to use

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I ve seen this idiom employed in many codes and I m pretty sure I ve even seen it somewhere in Boost s libraries  However  as far as I remember the most common name is base  or Base  instead of super   This idiom is especially useful if working with template classes  As an example  consider the following class  from a real project    template  lt typename TText  typename TSpec gt  class Finder lt Index lt TText  PizzaChili lt TSpec gt   gt   PizzaChiliFinder gt        public Finder lt Index lt TText  PizzaChili lt TSpec gt   gt   Default gt        typedef Finder lt Index lt TText  PizzaChili lt TSpec gt   gt   Default gt  TBase                 Don t mind the funny names  The important point here is that the inheritance chain uses type arguments to achieve compile-time polymorphism  Unfortunately  the nesting level of these templates gets quite high  Therefore  abbreviations are crucial for readability and maintainability

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One problem with this is that if you forget to  re- define super for derived classes  then any call to super  something will compile fine but will probably not call the desired function   For example   class Base   public   virtual void foo               class Derived  public Base   public      typedef Base super      virtual void foo                 super  foo         call superclass implementation             do other stuff                       class DerivedAgain  public Derived   public      virtual void foo                    Call superclass function         super  foo          oops  calls Base  foo   rather than Derived  foo                            As pointed out by Martin York in the comments to this answer  this problem can be eliminated by making the typedef private rather than public or protected

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I ve seen this idiom employed in many codes and I m pretty sure I ve even seen it somewhere in Boost s libraries  However  as far as I remember the most common name is base  or Base  instead of super   This idiom is especially useful if working with template classes  As an example  consider the following class  from a real project    template  lt typename TText  typename TSpec gt  class Finder lt Index lt TText  PizzaChili lt TSpec gt   gt   PizzaChiliFinder gt        public Finder lt Index lt TText  PizzaChili lt TSpec gt   gt   Default gt        typedef Finder lt Index lt TText  PizzaChili lt TSpec gt   gt   Default gt  TBase                 Don t mind the funny names  The important point here is that the inheritance chain uses type arguments to achieve compile-time polymorphism  Unfortunately  the nesting level of these templates gets quite high  Therefore  abbreviations are crucial for readability and maintainability

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Bjarne Stroustrup mentions in Design and Evolution of C   that super as a keyword was considered by the ISO C   Standards committee the first time C   was standardized   Dag Bruck proposed this extension  calling the base class  inherited    The proposal mentioned the multiple inheritance issue  and would have flagged ambiguous uses   Even Stroustrup was convinced   After discussion  Dag Bruck  yes  the same person making the proposal  wrote that the proposal was implementable  technically sound  and free of major flaws  and handled multiple inheritance   On the other hand  there wasn t enough bang for the buck  and the committee should handle a thornier problem   Michael Tiemann arrived late  and then showed that a typedef ed super would work just fine  using the same technique that was asked about in this post   So  no  this will probably never get standardized   If you don t have a copy  Design and Evolution is well worth the cover price   Used copies can be had for about  10

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I ve quite often seen it used  sometimes as super t  when the base is a complex template type  boost  iterator adaptor does this  for example

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After migrating from Turbo Pascal to C   back in the day  I used to do this in order to have an equivalent for the Turbo Pascal  inherited  keyword  which works the same way  However  after programming in C   for a few years I stopped doing it  I found I just didn t need it very much

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FWIW Microsoft has added an extension for   super in their compiler

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I just found an alternate workaround   I have a big problem with the typedef approach which bit me today    The typedef requires an exact copy of the class name   If someone changes the class name but doesn t change the typedef then you will run into problems    So I came up with a better solution using a very simple template   template  lt class C gt  struct MakeAlias   C        typedef C BaseAlias       So now  instead of  class Derived   public Base   private      typedef Base Super       you have  class Derived   public MakeAlias lt Base gt           Can refer to Base as BaseAlias here      In this case  BaseAlias is not private and I ve tried to guard against careless usage by selecting an type name that should alert other developers

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One additional reason to use a typedef for the superclass is when you are using complex templates in the object s inheritance   For instance   template  lt typename T  size t C  typename U gt  class A           template  lt typename T gt  class B   public A lt T 99 T gt             In class B it would be ideal to have a typedef for A otherwise you would be stuck repeating it everywhere you wanted to reference A s members   In these cases it can work with multiple inheritance too  but you wouldn t have a typedef named  super   it would be called  base A t  or something like that   --jeffk

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After migrating from Turbo Pascal to C   back in the day  I used to do this in order to have an equivalent for the Turbo Pascal  inherited  keyword  which works the same way  However  after programming in C   for a few years I stopped doing it  I found I just didn t need it very much

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One problem with this is that if you forget to  re- define super for derived classes  then any call to super  something will compile fine but will probably not call the desired function   For example   class Base   public   virtual void foo               class Derived  public Base   public      typedef Base super      virtual void foo                 super  foo         call superclass implementation             do other stuff                       class DerivedAgain  public Derived   public      virtual void foo                    Call superclass function         super  foo          oops  calls Base  foo   rather than Derived  foo                            As pointed out by Martin York in the comments to this answer  this problem can be eliminated by making the typedef private rather than public or protected

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I don t recall seeing this before  but at first glance I like it   As Ferruccio notes  it doesn t work well in the face of MI  but MI is more the exception than the rule and there s nothing that says something needs to be usable everywhere to be useful

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I don t recall seeing this before  but at first glance I like it   As Ferruccio notes  it doesn t work well in the face of MI  but MI is more the exception than the rule and there s nothing that says something needs to be usable everywhere to be useful

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I don t know whether it s rare or not  but I ve certainly done the same thing   As has been pointed out  the difficulty with making this part of the language itself is when a class makes use of multiple inheritance

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I use the   super keyword  But it s Microsoft specific   http   msdn microsoft com en-us library 94dw1w7x aspx

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One additional reason to use a typedef for the superclass is when you are using complex templates in the object s inheritance   For instance   template  lt typename T  size t C  typename U gt  class A           template  lt typename T gt  class B   public A lt T 99 T gt             In class B it would be ideal to have a typedef for A otherwise you would be stuck repeating it everywhere you wanted to reference A s members   In these cases it can work with multiple inheritance too  but you wouldn t have a typedef named  super   it would be called  base A t  or something like that   --jeffk

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