Disable copy constructor

Question

I have a class    class SymbolIndexer   protected    SymbolIndexer          public    static inline SymbolIndexer  amp  GetUniqueInstance               static SymbolIndexer uniqueinstance        return uniqueinstance              How should I modify it to disable code like   SymbolIndexer symbol indexer    SymbolIndexer  GetUniqueInstance        and only allow code like    SymbolIndexer  amp  ref symbol indexer    SymbolIndexer  GetUniqueInstance

User · Answer

Make SymbolIndexer  const SymbolIndexer amp    private  If you re assigning to a reference  you re not copying

User · Answer

If you don t mind multiple inheritance  it is not that bad  after all   you may write simple class with private copy constructor and assignment operator and additionally subclass it   class NonAssignable   private      NonAssignable NonAssignable const amp        NonAssignable amp  operator  NonAssignable const amp    public      NonAssignable          class SymbolIndexer  public Indexer  public NonAssignable        For GCC this gives the following error message   test h  In copy constructor    SymbolIndexer  SymbolIndexer const SymbolIndexer amp       test h  error     NonAssignable  NonAssignable const NonAssignable amp      is private   I m not very sure for this to work in every compiler  though  There is a related question  but with no answer yet   UPD   In C  11 you may also write NonAssignable class as follows   class NonAssignable   public      NonAssignable NonAssignable const amp     delete      NonAssignable amp  operator  NonAssignable const amp     delete      NonAssignable           The delete keyword prevents members from being default-constructed  so they cannot be used further in a derived class s default-constructed members  Trying to assign gives the following error in GCC   test cpp  error  use of deleted function              SymbolIndexer amp  SymbolIndexer  operator  const SymbolIndexer amp      test cpp  note     SymbolIndexer amp  SymbolIndexer  operator  const SymbolIndexer amp                is implicitly deleted because the default definition would           be ill-formed    UPD   Boost already has a class just for the same purpose  I guess it s even implemented in similar way  The class is called boost  noncopyable and is meant to be used as in the following    include  lt boost core noncopyable hpp gt   class SymbolIndexer  public Indexer  private boost  noncopyable        I d recommend sticking to the Boost s solution if your project policy allows it  See also another boost  noncopyable-related question for more information

User · Answer

You can make the copy constructor private and provide no implementation   private      SymbolIndexer const SymbolIndexer amp      Or in C  11  explicitly forbid it   SymbolIndexer const SymbolIndexer amp     delete

[c++] Disable copy constructor

Examples related to c++

Examples related to copy-constructor