pragma.dd

Ddoc

$(SPEC_S Pragmas,

$(GRAMMAR
$(GNAME Pragma):
    $(B pragma) $(B $(LPAREN)) $(I Identifier) $(B $(RPAREN))
    $(B pragma) $(B $(LPAREN)) $(I Identifier) $(B ,) $(GLINK2 expression, ArgumentList) $(B $(RPAREN))
)


        $(P Pragmas are a way to pass special information to the compiler
        and to add vendor specific extensions to D.
        Pragmas can be used by themselves terminated with a $(SINGLEQUOTE ;),
        they can influence a statement, a block of statements, a declaration, or
        a block of declarations.
        )

        $(P Pragmas can appear as either declarations,
        $(I Pragma) $(GLINK2 attribute, DeclarationBlock),
        or as statements,
        $(GLINK2 statement, PragmaStatement).
        )

-----------------
pragma(ident);        // just by itself

pragma(ident) declaration; // influence one declaration

pragma(ident): // influence subsequent declarations
    declaration;
    declaration;

pragma(ident) { // influence block of declarations
    declaration;
    declaration;
}

pragma(ident) statement; // influence one statement

pragma(ident) { // influence block of statements
    statement;
    statement;
}
-----------------

        $(P The kind of pragma it is is determined by the $(I Identifier).
        $(I ExpressionList) is a comma-separated list of
        $(ASSIGNEXPRESSION)s. The $(ASSIGNEXPRESSION)s must be
        parsable as expressions, but what they mean semantically
        is up to the individual pragma semantics.
        )

<h2><a name="Predefined-Pragmas">Predefined Pragmas</a></h2>

        $(P All implementations must support these, even if by just ignoring
        them:
        )

    $(DL

    $(DT $(B msg))
    $(DD Prints a message while compiling, the $(ASSIGNEXPRESSION)s must
        be string literals:
-----------------
pragma(msg, "compiling...");
-----------------
    )

    $(DT $(B lib))
    $(DD Inserts a directive in the object file to link in the library
        specified by the $(ASSIGNEXPRESSION).
        The $(ASSIGNEXPRESSION)s must be a string literal:
-----------------
pragma(lib, "foo.lib");
-----------------
    )
$(V2
    $(DT $(B startaddress))
    $(DD Puts a directive into the object file saying that the
        function specified in the first argument will be the
        start address for the program:
-----------------
void foo() { ... }
pragma(startaddress, foo);
-----------------
        This is not normally used for application level programming,
        but is for specialized systems work.
        For applications code, the start address is taken care of
        by the runtime library.
    )
)

    )

<h2>Vendor Specific Pragmas</h2>

        $(P Vendor specific pragma $(I Identifier)s can be defined if they
        are prefixed by the vendor's trademarked name, in a similar manner
        to version identifiers:
        )

-----------------
pragma(DigitalMars_funky_extension) { ... }
-----------------

        $(P Compilers must diagnose an error for unrecognized $(I Pragma)s,
        even if they are vendor specific ones. This implies that vendor
        specific pragmas should be wrapped in version statements:
        )

-----------------
version (DigitalMars)
{
    pragma(DigitalMars_funky_extension)
    { ... }
}
-----------------

)

Macros:
        TITLE=Pragmas
        WIKI=Pragma
        CATEGORY_SPEC=$0