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pointers_to_members pragma

C++ Specific

Specifies whether a pointer to a class member can be declared before its associated class definition. Used to control the pointer size, and the code required to interpret the pointer.

Syntax

#pragma pointers_to_members( best_case )
#pragma pointers_to_members( full_generality [ , most-general-representation ] )

Remarks

You can place a pointers_to_members pragma in your source file as an alternative to using the /vmb or /vmg and /vmm, /vms, /vmv compiler options or the Microsoft-specific inheritance keywords.

The pointer-declaration argument specifies whether you've declared a pointer to a member before or after the associated function definition. The pointer-declaration argument is one of these two symbols:

  • full_generality
    Generates safe, sometimes nonoptimal code. Use full_generality if any pointer to a member is declared before the associated class definition. This argument always uses the pointer representation specified by the most-general-representation argument. Equivalent to /vmg.

  • best_case
    Generates optimal code using best-case representation for all pointers to members. Requires you to define the class before you declare a pointer to a member. The default is best_case.

The most-general-representation argument specifies the smallest pointer representation that the compiler should use to reference safely any pointer to a member of a class in a translation unit. The argument can be one of these values:

  • single_inheritance
    The most general representation is single-inheritance pointer to member function. Equivalent to /vmg /vms. Causes an error if the inheritance model of a class definition is either multiple or virtual.

  • multiple_inheritance
    The most general representation is multiple-inheritance pointer to member function. Equivalent to /vmg /vmm. Causes an error if the inheritance model of a class definition is virtual.

  • virtual_inheritance
    The most general representation is virtual-inheritance pointer to member function. Equivalent to /vmg /vmv. Never causes an error. virtual_inheritance is the default argument when #pragma pointers_to_members(full_generality) is used.

Caution

We advise you to put the pointers_to_members pragma only in the source code file that you want to affect, and only after any #include directives. This practice reduces the risk that the pragma will affect other files, and that you'll accidentally specify multiple definitions for the same variable, function, or class name.

Example

//   Specify single-inheritance only
#pragma pointers_to_members( full_generality, single_inheritance )

END C++ Specific

See also

Pragma directives and the __pragma and _Pragma keywords