What is a method group in C

Question

I have often encountered an error such as  cannot convert from  method group  to  string   in cases like    var list   new List lt string gt            snip list Add someObject ToString     of course there was a typo in the last line because I forgot the invocation parentheses after ToString  The correct form would be   var list   new List lt string gt            snip list Add someObject ToString         lt - notice the parentheses   However I came to wonder what is a method group  Google isn t much of a help nor MSDN

User · Answer

The ToString function has many overloads - the method group would be the group consisting of all the different overloads for that function

User · Answer

The first result in your MSDN search said      The method group identifies the one   method to invoke or the set of   overloaded methods from which to   choose a specific method to invoke   my understanding is that basically because when you just write someInteger ToString  it may refer to   Int32 ToString IFormatProvider     or it can refer to   Int32 ToString     so it is called a method group

User · Answer

A method group is the name for a set of methods  that might be just one  - i e  in theory the ToString method may have multiple overloads  plus any extension methods   ToString    ToString string format   etc - hence ToString by itself is a  method group    It can usually convert a method group to a  typed  delegate by using overload resolution - but not to a string etc  it doesn t make sense   Once you add parentheses  again  overload resolution kicks in and you have unambiguously identified a method call

User · Answer

Also  if you are using LINQ  you can apparently do something like myList Select methodGroup    So  for example  I have   private string DoSomethingToMyString string input           blah     Instead of explicitly stating the variable to be used like this   public List lt string gt  GetStringStuff         return something getStringsFromSomewhere Select str   gt  DoSomethingToMyString str        I can just omit the name of the var   public List lt string gt  GetStringStuff         return something getStringsFromSomewhere Select DoSomethingToMyString

User · Answer

You can cast a method group into a delegate   The delegate signature selects 1 method out of the group   This example picks the ToString   overload which takes a string parameter   Func lt string string gt  fn   123 ToString  Console WriteLine fn  00000000       This example picks the ToString   overload which takes no parameters   Func lt string gt  fn   123 ToString  Console WriteLine fn

[c#] What is a method group in C#?

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