Component bslmf_addvolatile [Package bslmf]

Provide a meta-function for adding a volatile-qualifier. More...

Namespaces
namespace	bslmf
namespace	bsl

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Detailed Description

Outline

• Purpose
• Classes
• Description
  • Usage
    • Example 1: Adding a volatile-Qualifier to a Type

Purpose:

Provide a meta-function for adding a volatile-qualifier.

Classes:

bsl::add_volatile	meta-function for adding top-level volatile-qualifier
bsl::add_volatile_t	alias to the return type of the bsl::add_volatile

See also:

Component bslmf_removevolatile

Description:

This component defines a meta-function, bsl::add_volatile and declares an bsl::add_volatile_t alias to the return type of the bsl::add_volatile, that may be used to add a top-level volatile-qualifier to a type if it is not a reference type, nor a function type, nor already volatile-qualified at the top-level.

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

Usage:

In this section we show intended use of this component.

Example 1: Adding a volatile-Qualifier to a Type:

Suppose that we want to add a volatile-qualifier to a particular type.

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

  typedef int          MyType;
  typedef volatile int MyVolatileType;

Now, we add a volatile-qualifier to MyType using bsl::add_volatile and verify that the resulting type is the same as MyVolatileType:

  assert(true ==
     (bsl::is_same<bsl::add_volatile<MyType>::type, MyVolatileType>::value));

Finally, if the current compiler supports alias templates C++11 feature, we add a volatile-qualifier to MyType using bsl::add_volatile_t and verify that the resulting type is the same as MyVolatileType:

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

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