Confusion about decorators

[Henrik Faber]

On 12.12.2011 14:37, Andrea Crotti wrote:
> On 12/12/2011 01:27 PM, Henrik Faber wrote:
>> Hi group,
>>
>> I'm a bit confused regarding decorators. Recently started playing with
>> them with Python3 and wanted (as an excercise) to implement a simple
>> type checker first: I know there are lots of them out there, this is
>> actually one of the reasons I chose that particular function (to compare
>> my solution against other, proven solutions).
>
> Not sure how that could work in general, what does "bar: str" should do?
> Is that a dictionary?

No. It's PEP 3107 function annotations.

> Anyway there is already an implementation if you're interested for type
> checking:
> http://oakwinter.com/code/typecheck/

*sigh* no, not really -- this is exactly why I wrote "I know there are
lots of them out there". I've actually seen and run
http://code.activestate.com/recipes/577299-method-signature-type-checking-decorator-for-pytho/

However, this doesn't do it for me -- I want to know why my solution
fails, not just use some other solution without really understanding it.
I really would like to understand what's going on.

I'm especially puzzled about the fact that in my solution, __call__ is
called with only the method's arguments (i.e. "fooobar") in my example
instead of two arguments (self, "fooobar").

Best regards,
Henrik