[m-dev.] context "macros"

[Julien Fischer]

On Wed, 26 Mar 2008, Ralph Becket wrote:

> Julien Fischer, Tuesday, 25 March 2008:
>>
>> On Tue, 25 Mar 2008, Peter Wang wrote:
>>
>>> What do you think of adding support for __file__, __pred__, __line__
>>> "macros"?  These would expand into strings or integers like the
>>> corresponding C macros.
>>
>> I have often though something like this would be useful, particularly
>> given that the this_file/0 functions we use in the compiler don't
>> extend well when sub-modules are involved (you have to qualify them
>> if the parent also defines a this_file/0 function.)
>>
>>> My concern was just about the syntax.  __foo__ has the advantages of
>>> following C and requiring no changes to the parser.
>>
>>> __line__ is a
>>> little bit sticky for referential transparency, but __file__ and
>>> __pred__ would just act like variables assigned at the start of the
>>> predicate.
>>
>> An alternative syntax suggestion: @line@, @file@ etc ...
>
> We haven't used the # symbol yet, as I recall.

Yes we do, it is used with #line directives (ref. man 2.2).

(On an slightly related matter I think we should replace pragma
source_file with #file.)

Julien.
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