Metasyntax/Macros

[Paddy McCarthy]

alloydflanagan at attbi.com (A. Lloyd Flanagan) wrote in message news:<a8b7f07a.0305141356.344f0e69 at posting.google.com>...
> paddy3118 at netscape.net (Paddy McCarthy) wrote in message news:<2ae25c6b.0305140003.dbd812e at posting.google.com>...
> <excerpt>
> > and create a Python class. By choosing a careful set of macros the
> > resultant {ython-with-macros source could be understandable to people
> > with only the domain specific language knowledge,
> > 
> </expert>
> 
> And only those people.  The trouble with macros in general, and C
> macros in particular, is that they can be used to mangle the language
> into almost any form the macro-writer wants.  The result is something
> that does not make sense to any other person on the planet.
> 
> IMHO, we already have plenty of languages that are ideal for writing
> unreadable code.  Let's not turn Python into one of them.
> 
> If you want a language with a powerful designed-in macro facility,
> check out Lisp.

But that *is* the point. I don't want a Lisp or a C or a Rebol macro
facility.
I just have not closed my mind to the thought of macros within Python.
I just haven't thought of a pythonic way of doing it.

Any implimentation I guess would have to include modification and
introspection of the parser so something like help(__statements__) and
help(__operators__) would print the docstrings of statements together
with details on how the statement is parsed, or the associativity etc
of operators (including the built-in ones).

As for producing code that no one can read: Yes! Documentation and
introspection must be a part of a good Python macro system but I think
it is analogous to using a package. Unless you read-up about it, you
don't know what a package does. Python helps by having things like
help(). For any proposed macro solution Python would need appropriate
help and debugging extensions!

Maybe the default behavior when in interactive mode could be for each
macro instance to have its expansion printed when it is encountered.
This default could be then be optionally turned off.