Component bslmf_ismemberpointer [Package bslmf]

Provide a compile-time check for non-static member pointer types. More...

Classes
struct	bsl::is_member_pointer< t_TYPE >
struct	bsl::is_member_pointer< t_TARGET_TYPE t_HOST_TYPE::* >
struct	bsl::is_member_pointer< t_TARGET_TYPE t_HOST_TYPE::*const >
struct	bsl::is_member_pointer< t_TARGET_TYPE t_HOST_TYPE::*volatile >
struct	bsl::is_member_pointer< t_TARGET_TYPE t_HOST_TYPE::*const volatile >

---

Detailed Description

Outline

• Purpose
• Classes
• Description
  • Usage
    • Example 1: Verify Member Pointer Types

Purpose:

Provide a compile-time check for non-static member pointer types.

Classes:

bsl::is_member_pointer	standard meta-function for member pointer types
bsl::is_member_pointer_v	the result value of the standard meta-function

See also:

Component bslmf_ismemberfunctionpointer, Component bslmf_ismemberobjectpointer

Description:

This component defines a meta-function, bsl::is_member_pointer and a template variable bsl::is_member_pointer_v, that represents the result value of the bsl::is_member_pointer meta-function, that may be used to query whether a type is a pointer to non-static member type.

bsl::is_member_pointer meets the requirements of the is_member_pointer template defined in the C++11 standard [meta.unary.comp].

Note that the template variable is_member_pointer_v is defined in the C++17 standard as an inline variable. If the current compiler supports the inline variable C++17 compiler feature, bsl::is_member_pointer_v is defined as an inline constexpr bool variable. Otherwise, if the compiler supports the variable templates C++14 compiler feature, bsl::is_member_pointer_v is defined as a non-inline constexpr bool variable. See BSLS_COMPILERFEATURES_SUPPORT_INLINE_VARIABLES and BSLS_COMPILERFEATURES_SUPPORT_VARIABLE_TEMPLATES macros in bsls_compilerfeatures component for details.

Usage:

In this section we show intended use of this component.

Example 1: Verify Member Pointer Types:

Suppose that we want to assert whether a set of types are member pointer types.

First, we create a user-defined type MyStruct:

  struct MyStruct
  {
  };

Now, we create three typedefs -- a member object pointer type, a member function pointer type and a general function pointer type:

  typedef int MyStruct::* DataMemPtr;
  typedef int (MyStruct::*MyStructMethodPtr) ();
  typedef int (*MyFunctionPtr) ();

Finally, we instantiate the bsl::is_member_pointer template for various types and assert the value static data member of each instantiation:

  assert(false == bsl::is_member_pointer<int*>::value);
  assert(false == bsl::is_member_pointer<MyFunctionPtr>::value);
  assert(true  == bsl::is_member_pointer<DataMemPtr>::value);
  assert(true  == bsl::is_member_pointer<MyStructMethodPtr>::value);

Note that if the current compiler supports the variable templates C++14 feature then we can re-write the snippet of code above using the bsl::is_member_pointer_v variable as follows:

#ifdef BSLS_COMPILERFEATURES_SUPPORT_VARIABLE_TEMPLATES
  assert(false == bsl::is_member_pointer_v<int*>);
  assert(false == bsl::is_member_pointer_v<MyFunctionPtr>);
  assert(true  == bsl::is_member_pointer_v<DataMemPtr>);
  assert(true  == bsl::is_member_pointer_v<MyStructMethodPtr>);
#endif