| title | pointers_to_members pragma | ||||
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| ms.date | 08/29/2019 | ||||
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| ms.assetid | 8325428c-c90a-4aed-9e82-cb1dda23f4ca |
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.
#pragma pointers_to_members( pointer-declaration [ , most-general-representation ] )
You can place a pointers_to_members pragma in your source file as an alternative to using the /vmb or /vmg compiler options or the 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 the following two symbols:
| Argument | Comments |
|---|---|
| full_generality | Generates safe, sometimes nonoptimal code. You 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 safe, optimal code using best-case representation for all pointers to members. Requires defining the class before declaring a pointer to a member of the class. The default is best_case. |
The most-general-representation argument specifies the smallest pointer representation that the compiler can safely use to reference any pointer to a member of a class in a translation unit. The argument can be one of these values:
| Argument | Comments |
|---|---|
| single_inheritance | The most general representation is single-inheritance, pointer to a member function. Causes an error if the inheritance model of a class definition for which a pointer to a member is declared is ever either multiple or virtual. |
| multiple_inheritance | The most general representation is multiple-inheritance, pointer to a member function. Causes an error if the inheritance model of a class definition for which a pointer to a member is declared is virtual. |
| virtual_inheritance | The most general representation is virtual-inheritance, pointer to a member function. 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 lessens the risk that the pragma will affect other files, and that you will accidentally specify multiple definitions for the same variable, function, or class name.
// Specify single-inheritance only
#pragma pointers_to_members( full_generality, single_inheritance )END C++ Specific