a translation of #undef

[ToutEnMasm]

Hello,
I write a translator of the header files for masm and I don't find the equivalent of #undef.
#define _X86_    can be translate by  _X86_ equ
but #undef _X86_    ,I don't see how to translate.
            If somebody have an idea  ..., ToutEnMasm

[Jeff]

AFAIK, there is no equivalent in MASM.  i wanted to be able to do the same as well but couldnt.  its a shame we cant use PURGE.

[MazeGen]

That's one of the weak points of MASM - there's really nothing like #undef.

There's a trick how to redefine text macro without the need of #undefine, but it is another story.

[Vortex]

There's a trick how to redefine text macro without the need of #undefine, but it is another story.

Could you explain that method?

[Jeff]

text macros can be redefined if they were defined with the TEXTEQU directive.  ;)

[Vortex]

Hi Jeff,

This one works fine :

Code Select Expand


v TEXTEQU <trial>
v TEXTEQU


[MazeGen]

You can encounter this problem in some complex macro, when the symbolic name of the text macro is variable.
Because it seems to be too difficult to give clear sample proof of the solution, here is just what I was talking about:

Code Select Expand


SomeStr TEXTEQU <SymbolicName> ; SomeStr = "SymbolicName"
%SomeStr TEXTEQU <I Am A String> ; SymbolicName = "I Am A String"


Without the possibility of undefine the SomeStr macro, we can't simply redefine it:

Code Select Expand


SomeStr TEXTEQU <SymbolicName> ; SomeStr = "I Am A String"
%SomeStr TEXTEQU <I Am A String> ; I Am A String = "I Am A String"


The last statement, I Am A String = "I Am A String", is not valid - assembly error.

Try it:

Code Select Expand


.686
.model flat, stdcall

SomeStr TEXTEQU <SymbolicName>
%ECHO SomeStr

%SomeStr TEXTEQU <I Am A String>
%ECHO SomeStr

SomeStr TEXTEQU <SymbolicName>
%ECHO SomeStr

%SomeStr TEXTEQU <I Am A String> ; error
%ECHO SomeStr

.code
start:
end start