bslmf_isintegral

Detailed Description

Outline

• Purpose
• Classes
• Description
  • Usage
    • Example 1: Verify Integral Types

Purpose

Provide a compile-time check for integral types.

Classes

• bsl::is_integral: standard meta-function for determining integral types
• bsl::is_integral_v: the result value of bsl::is_integral

See also

bslmf_integralconstant

Description

This component defines a meta-function, bsl::is_integral and a template variable bsl::is_integral_v, that represents the result value of the bsl::is_integral meta-function, that may be used to query whether a type is an integral type as defined in section 3.9.1.7 of the C++11 standard [basic.fundamental] (excluding those types that were introduced in C++11).

bsl::is_integral meets the requirements of the is_integral template defined in the C++11 standard [meta.unary.cat] except that it may not correctly evaluate types introduced in C++11.

Note that the template variable is_integral_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_integral_v is defined as an inline constexpr bool variable. Otherwise, if the compiler supports the variable templates C++14 compiler feature, bsl::is_integral_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 Integral Types

Suppose that we want to assert whether a particular type is an integral type.

First, we create two typedefs – an integral type and a non-integral type:

typedef void MyType;
typedef int  MyIntegralType;

Now, we instantiate the bsl::is_integral template for each of the typedefs and assert the value static data member of each instantiation:

assert(false == bsl::is_integral<MyType>::value);
assert(true  == bsl::is_integral<MyIntegralType>::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_integral_v variable as follows:

#ifdef BSLS_COMPILERFEATURES_SUPPORT_VARIABLE_TEMPLATES
  assert(false == bsl::is_integral_v<MyType>);
  assert(true  == bsl::is_integral_v<MyIntegralType>);
#endif