forward keyword in macro

[Emil_halim]

what does the keyword forward meaning in the next program?

how is job of the "theVar" in the macro and how it replaced with the i variable?

Code Select Expand


program InitDemo;
#include( "stdlib.hhf" )

    #macro init_int32( initVal ):theVar;
   
        forward( theVar );
        theVar:int32;
        ?_initialize_ :=
                _initialize_ +
                "mov( " +
                @string:initVal +
                ", " +
                @string:theVar +
                " );";
    #endmacro
                       
var
    i:init_int32( 1 );
   
begin InitDemo;

    stdout.put( "i=", i, nl );
                   
end InitDemo;


[Sevag.K]

what does the keyword forward meaning in the next program?

how is job of the "theVar" in the macro and how it replaced with the i variable?

forward is a special keyword that 'looks back' on the line of the macro declaration to find the identifier declared right before the macro in the source and text equates the identifier with the parameter passed in forward.  doing so will make the entire declaration a part of the macro expansion.

so in the example below, having
i:init_32( 1 );

theVar in the macro will become a text constant of the the letter 'i'

now that theVar represents 'i', the next line in the macro
theVar:int32;

is the same as saying i:int32;

the next part, ?_initialize will expand after the begin statement.
so after begin InitDemo, the macro will expand this code:

mov( 1, i  );

Code Select Expand


program InitDemo;
#include( "stdlib.hhf" )

    #macro init_int32( initVal ):theVar;
   
        forward( theVar );
        theVar:int32;
        ?_initialize_ :=
                _initialize_ +
                "mov( " +
                @string:initVal +
                ", " +
                @string:theVar +
                " );";
    #endmacro
                       
var
    i:init_int32( 1 );
   
begin InitDemo;

    stdout.put( "i=", i, nl );
                   
end InitDemo;


[Emil_halim]

thanks.