bslx_versionfunctions

Detailed Description

Outline

• Purpose
• Classes
• Description
  • Usage
    • Example 1: Querying BDEX Version

Purpose

Provide functions to return BDEX version information for types.

Classes

• bslx::VersionFunctions: namespace for functions returning version numbers

Description

This component provides a namespace, bslx::VersionFunctions, that contains functions for determining the BDEX version number for types.

This namespace defines the maxSupportedBdexVersion function, which is overloaded to return a predetermined value, k_NO_VERSION, also defined in this namespace, for each of the fundamental types, enum types, and bsl::string. For bsl::vector, the maxSupportedBdexVersion function returns 1 if the vector is parameterized on one of the three types mentioned above. Otherwise, the version number returned is the same as that returned for bsl::vector::value_type. For BDEX-compliant types, the function returns the BDEX version number returned by the maxSupportedBdexVersion method provided by that type.

In general, this component is used by higher-level bslx components to query the version number for types.

Usage

This section illustrates intended use of this component.

Example 1: Querying BDEX Version

This component may be used by clients to query the version number for types in a convenient manner. First, define an enum, my_Enum:

enum my_Enum {
    ENUM_VALUE1,
    ENUM_VALUE2,
    ENUM_VALUE3,
    ENUM_VALUE4
};

Then, define a BDEX-compliant class, my_Class:

class my_Class {
  public:
    enum {
        VERSION = 1
    };
 
    // CLASS METHODS
    static int maxSupportedBdexVersion(int) {
        return VERSION;
    }
 
    // ...
 
};

Finally, verify the value returned by maxSupportedBdexVersion for some fundamental types, my_Enum, and my_Class with an arbitrary versionSelector:

using bslx::VersionFunctions::maxSupportedBdexVersion;
using bslx::VersionFunctions::k_NO_VERSION;
 
assert(k_NO_VERSION ==
    maxSupportedBdexVersion(reinterpret_cast<char        *>(0), 20131127));
assert(k_NO_VERSION ==
    maxSupportedBdexVersion(reinterpret_cast<int         *>(0), 20131127));
assert(k_NO_VERSION ==
    maxSupportedBdexVersion(reinterpret_cast<double      *>(0), 20131127));
assert(k_NO_VERSION ==
    maxSupportedBdexVersion(reinterpret_cast<bsl::string *>(0), 20131127));
 
assert(k_NO_VERSION ==
    maxSupportedBdexVersion(reinterpret_cast<my_Enum     *>(0), 20131127));
 
assert(my_Class::VERSION ==
    maxSupportedBdexVersion(reinterpret_cast<my_Class    *>(0), 20131127));