other ways to check for <type 'function'>?

[Christophe]

Re: other ways to check for &lt;type 'function'&gt;?

Christophe a écrit :

Sybren Stuvel a écrit :

>Christophe enlightened us with:

>>I don't think it's a good idea because when you place a try catch
>>block around a function call, you'll catch any exception thrown by
>>the function itself and not only the "cannot be called" exception.

>>
>That depends on the exception you're catching, doesn't it?

>
And what if the function has an error and calls a non callable object ?

Or even worse. Since we have :

>>None()

Traceback (most recent call last):
File "<stdin>", line 1, in ?
TypeError: 'NoneType' object is not callable

>>1+""

Traceback (most recent call last):
File "<stdin>", line 1, in ?
TypeError: unsupported operand type(s) for +: 'int' and 'str'

>>""+1

Traceback (most recent call last):
File "<stdin>", line 1, in ?
TypeError: cannot concatenate 'str' and 'int' objects

All of them are TypeError exceptions. It is extremly dangerous to put a
try except TypeError clause around a function call to catch the case
where the function object isn't a callable :/

[Fredrik Lundh]

Re: other ways to check for &lt;type 'function'&gt;?

elderic wrote:

I just wanted to know if there was a keyword for functions, too.
>
Then u could've done: type(f) is function
quite similar to: type(x) is int

but why do you think you need that, when you have callable() ? unless
you're doing specialized stuff, there's really no reason to distinguish
between function objects and other callables.

</F>

[elderic]

Re: other ways to check for &lt;type 'function'&gt;?

I just wanted to know if there was a keyword for functions, too.

Then u could've done: type(f) is function
quite similar to: type(x) is int

>
but why do you think you need that, when you have callable() ? unless
you're doing specialized stuff, there's really no reason to distinguish
between function objects and other callables.
>
</F>

I never said that I need anything - I merely asked for alternatives. =)
I'm pretty happy with the types-module or the callable() test.

Basically it's just for wrapping the creation of Tk-Buttons, etc.
They need a callback and in my process to learn I wanted to know about
the
possible options to test for that.

peace of mind. =)
elderic

[Fredrik Lundh]

Re: other ways to check for &lt;type 'function'&gt;?

elderic wrote:

I never said that I need anything - I merely asked for alternatives. =)
I'm pretty happy with the types-module or the callable() test.
>
Basically it's just for wrapping the creation of Tk-Buttons, etc.
They need a callback and in my process to learn I wanted to know about
the possible options to test for that.

the more reason not to even think about using anything but "callable".
many things in Python are callable; an explicit function test would
disallow several interesting alternatives:

>>def foo():

.... pass
....

>>class fum:

.... def bar(self):
.... pass
.... def __call__(self):
.... pass
....

>>type(foo) is type(fum)

False

>>f = fum()
>>type(foo) is type(f)

False

>>type(foo) is type(f.bar)

False

etc.

(and I really shouldn't ask why you cannot just use Tkinter, and spend
your time and energy on something more worthwhile ? if not else, there
are plenty of Tk extensions that could need nice wrappers...)

</F>

[eduardo.padoan@gmail.com]

Re: other ways to check for &lt;type 'function'&gt;?

Python should have a TypeError subclass: "NotCallableErr or", to enforce
BAFP.

[Ben Finney]

Re: other ways to check for &lt;type 'function'&gt;?

"eduardo.padoan @gmail.com" <eduardo.padoan @gmail.comwrite s:

Python should have a TypeError subclass: "NotCallableErr or", to
enforce BAFP.

Bureau of Alcohol, Firearms, and Programmers?

(Perhaps you meant "EAFP")

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Ben Finney