[Python-Dev] Re: pragmas as callbacks

[M.-A. Lemburg]

Greg Wilson wrote:
> 
> > > > 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:
> > > 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.
> 
> > Marc-Andre Lemburg:
> > I don't get your point: you can "program" the interpreter by
> > calling various sys module APIs to set interpreter flags already.
> >
> > Pragmas are needed to tell the compiler what to do with a
> > source file. They extend the command line flags which are already
> > available to a more fine-grained mechanism. That's all -- nothing
> > more.
> 
> Greg Wilson writes:
> I understand, but my experience with other languages indicates that once
> you have a way to set the parser's flags from within the source file being
> parsed, people are going to want to be able to do it conditionally, i.e.
> to set one flag based on the value of another.  Then they're going to want
> to see if particular flags have been set to something other than their
> default values, and so on.  Pragmas are a way to embed programs for the
> parser in the file being parsed.  If we're going to allow this at all, we
> will save ourselves a lot of future grief by planning for this now.

I don't think mixing compilation with execution is a good idea.

If we ever want to add this feature, we can always use a
pragma for it ;-) ...

def mysettings(compiler, locals, globals, target):
    compiler.setoptimization(2)

# Call the above hook for every new compilation block
pragma compiler_hook = "mysettings"

-- 
Marc-Andre Lemburg
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