Vax C90-EL SERIES Service Manual download pdf (Page 134)

Cray Standard C/C++ Reference Manual

In the case where the CC(1) command is given a single source file to compile and

link, all instantiations are done in the single source file and, by default, the used

mode is used and automatic instantiation is suppressed.

6.3 One Instantiation Per Object File

You can direct the prelinker to instantiate each template referenced in the source

into its own object file. This method is preferred over other template instantiation

object file generation options because:

• The user of a library pulls in only the instantiations that are needed.

• Multiple libraries with the same template can link. If each instantiation is not

placed in its own object file, linking a library with another library that also

contains the same instantiations will generate warnings on some platforms.

Use the -h one_instantiation_per_object option to generate one object

file per instantiation. For more information about this option, see Section 2.5.2,

page 12.

6.4 Instantiation #pragma Directives

Instantiation #pragma directives can be used in source code to control the

instantiation of specific template entities or sets of template entities. There are

three instantiation #pragma directives:

• The #pragma _CRI instantiate directive causes a specified entity to

be instantiated.

• The #pragma _CRI do_not_instantiate directive suppresses the

instantiation of a specified entity. It is typically used to suppress the

instantiation of an entity for which a specific definition is supplied.

• The #pragma _CRI can_instantiate directive indicates that a specified

entity can be instantiated in the current compilation, but need not be. It is

used in conjunction with automatic instantiation to indicate potential sites for

instantiation if the template entity is deemed to be required by the compiler.

The argument to the #pragma _CRI instantiate directive can be any of

the following:

• A template class name. For example: A<int>

• A template class declaration. For example: class A<int>

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Vax C90-EL SERIES Service Manual Page 134