[fasmg]Why do we use "!" in macro

The unconditional macros in fasmg are there mainly to allow defining constructions that in fasm required use of preprocessor's FIX directive.
What in fasm looked like:

Code:

macro foo name
{
        macro name arg
        \{ content_start
}

endfoo fix content_end } definition_end


foo test
        ; ...
endfoo

has the following equivalent in fasmg:

Code:

macro foo name
    esc macro name arg
        content_start
end macro

macro endfoo!
        content_end
    esc end macro
        definition_end
end macro


foo test
        ; ...
endfoo

The unconditional macros are closely related to what FIX does in fasm's preprocessor - the macro is simply replaced with its contents everywhere and unconditionally. If you try to make recursive unconditional macro, it is similar to defining self-referencing symbolic constant with EQU:

Code:

test equ test! ; this would expand till infinity, fasmg signals an error

l4m2 wrote:

What if uncondictional macro expanding only occur in the first layer?(when used it directly expand but wait when it is there again after expanding)

You can make something like this happen if you stack the unconditional macro on top of the conditional one, you can test this behavior with the following (highly artificial) sample:

Code:

macro test arg
        if arg > 0
        display `arg
end macro

macro test! arg
        test arg
        end if
end macro

        test 1

if 0
        test 2

That inner macro cannot be made recursive in such case, but you can still get recursion if you define the inner macro under a different name.