[ZODB-Dev] Persistent-derived class instances always callable

John Belmonte jvb at prairienet.org
Fri Oct 17 23:39:57 EDT 2003


Tim Peters wrote:
> I'm unclear why it's needed -- in over a decade of programming Python, the
> first time I used callable() was when typing the last reply <wink>.

I have a function that generates XML elements from a list of (Name, 
Content) tuples.  Normally the element content is set to str(Content), 
but if Content is a list I recurse, and if it is callable I call it and 
use the result.

> As is, ExtensionClass instances truly are callable as far as Python is
> concerned (they have a tp_call slot, which Python calls), and trying to
> convince Guido that "well, ya, they're callable, but not in a sense that's
> always useful to this particular app, so Python should grow some other idea
> of 'callable' that does make sense to this app" is going to be a hard sell.

It sounds like callable() as it is is useless, which is probably why 
you've never used it.  I suppose in my case I could just try calling 
every object and catch the TypeError.

-John


-- 
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