[Python-Dev] pragmas as callbacks

[Greg Wilson]

> Marc-Andre Lemburg wrote:
> I'd rather not add complicated semantics to pragmas -- they should be
> able to set flags, but not much more.

Greg Wilson writes:

That's probably what every Fortran compiler vendor said at first --- "just
a couple of on/off flags".  Then it was, "Set numeric values (like the
debugging level)".  A full-blown HPF compiler's pragmas are now a complete
programming language, so that you can (for example) specify how to
partition one array based on the partitioning in another.

Same thing happened with the C preprocessor --- more and more directives
crept in over time.  And the Microsoft C++ compiler.  And I'm sure this
list's readers could come up with dozens of more examples.

Pragmas are a way to give instructions to the interpreter; when you let
people give something instructions, you're letting them program it, and I
think it's best to design your mechanism from the start to support that.

Greg "oh no, not another parallelization directive" Wilson