[Python-Dev] 2.4a2, and @decorators

[Guido van Rossum]

> The only real necessary restriction on the @ operator is that its
> argument be callable and take a single argument. Many expressions
> could return a callable object. Why not let them? Is it really worth
> having a special case just to SyntaxError expressions that sometimes
> won't result in an appropriate callable?
> 
> Things someone might want to do, ordered roughly from most reasonable 
> to least reasonable ;)
> @foo().bar()
> @foo or bar
> @mydecorators['foo']
> @lambda f: foo(f) or bar(f)
> 
> Why disallow these forms? It seems quite difficult, especially, to 
> explain why the first one does not, or should not, work.

I have a gut feeling about this one.  I'm not sure where it comes
from, but I have it.  It may be that I want the compiler to be able to
recognize certain decorators.

So while it would be quite easy to change the syntax to @test in the
future, I'd like to stick with the more restricted form unless a real
use case is presented where allowing @test would increase readability.
(@foo().bar() doesn't count because I don't expect you'll ever need
that).

--Guido van Rossum (home page: http://www.python.org/~guido/)