[Python-Dev] Decorators with arguments are curries!

["Martin v. Löwis"]

Andrew Durdin wrote:
> def bar_decorator(func, param):
>     print param
>     return func
> 
> @foo_decorator
> @bar_decorator("one param here")
> def decorated_func():
>     pass
> 
> Here the first decorator statement is bare, while the second one
> includes parentheses and an argument; the first one looks like a
> function reference, while the second looks like a function call.

Correct. And that is indeed the intended meaning. Did you try this
out? It gives

Traceback (most recent call last):
   File "b.py", line 9, in ?
     @foo_decorator
TypeError: bar_decorator() takes exactly 2 arguments (1 given)

(although, as you can see, the line number is off by one)

See

http://www.python.org/dev/doc/devel/ref/function.html

on why this is so.

> Most of my concern here is that this aspect of decorator syntax
> appears to be implicitly introducing a currying syntax in one special
> circumstance, which is then *not* transferable to currying functions
> in normal situations, as it would conflict with function calling. 

And yet, the proposal does no such thing.

Regards,
Martin