Component bslmf_removeconst [Package bslmf]

Provide a meta-function for removing top-level const-qualifier. More...

Classes
struct	bsl::remove_const< t_TYPE >
struct	bsl::remove_const< t_TYPE const >

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Detailed Description

Outline

• Purpose
• Classes
• Description
  • Usage
    • Example 1: Removing the const-Qualifier of a Type

Purpose:

Provide a meta-function for removing top-level const-qualifier.

Classes:

bsl::remove_const	meta-function for removing top-level const-qualifier
bsl::remove_const_t	alias to the return type of the bsl::remove_const

See also:

Component bslmf_addconst

Description:

This component defines a meta-function, bsl::remove_const and declares an bsl::remove_const_t alias to the return type of the bsl::remove_const, that may be used to remove any top-level const-qualifier from a type.

bsl::remove_const and bsl::remove_const_t meet the requirements of the remove_const template defined in the C++11 standard [meta.trans.cv].

Usage:

In this section we show intended use of this component.

Example 1: Removing the const-Qualifier of a Type:

Suppose that we want to remove any top-level const-qualifier from a particular type.

First, we create two typedefs -- a const-qualified type (MyConstType) and the same type without the const-qualifier (MyType):

  typedef int       MyType;
  typedef const int MyConstType;

Now, we remove the const-qualifier from MyConstType using bsl::remove_const and verify that the resulting type is the same as MyType:

  assert(true ==
        (bsl::is_same<bsl::remove_const<MyConstType>::type, MyType>::value));

Finally, if the current compiler supports alias templates C++11 feature, we remove a const-qualifier from MyConstType using bsl::remove_const_t and verify that the resulting type is the same as MyType:

#ifdef BSLS_COMPILERFEATURES_SUPPORT_ALIAS_TEMPLATES
  assert(true ==
            (bsl::is_same<bsl::remove_const_t<MyConstType>, MyType>::value));
#endif

Note, that the bsl::remove_const_t avoids the ::type suffix and typename prefix when we want to use the result of the bsl::remove_const meta-function in templates.