[Python-Dev] A syntax for function attributes? (original) (raw)

Jeff Epler jepler@unpythonic.net
Wed, 30 Jul 2003 11:20:36 -0500

On Wed, Jul 30, 2003 at 08:38:13AM -0700, Mark Nottingham wrote:

I'm happy to write a PEP if that will help, but wanted to get a sense of what people's thinking was.

Well, if a function-modifier syntax is adopted (most frequently discussed in forms like def f() [modifier, modifier]: pass ) then a function-attribute modifier could sure be written: def attributes(*kw): def _attributes(f): for k, v in kw.iteritems(): setattr(f, k, v) return f return _attributes and used as follows (my example being of the 'type-hint' variety): def sqr(x) [optimize, attributes( return_type = float, argument_type = (float,), pure = True)]: return xx Of course, you could also do this: mathfunc = attribute(pure=true, return_type=float, argument_type=(float,)) def f(x) [optimze, mathfunc]: return x*x

Or the grammar for the modifier-list could be modified to accept 'name = expr' and 'expr', treating the former as creating a function attribute, and the latter as giving a modifier function: def sqr(x) [optimize, return_type = float, argument_type = (float,), pure = True]: return x*x

I don't think I'll be a big user of function attributes, as compared to function modifiers coughclassmethodcough, so perhaps I'm wrong to think that the latter should be done as a special case of the former. Certainly the [attributes()] approach will be harder for a parse-only tool to take advantage of, especially in the face of things like 'mathfunc = attribute(...)'. Is this an important feature for function attributes to have? What other reasons are there for a distinct syntax?

Jeff