Hello,
I need to recognize 'var' and ['var'], usually I would use:
if a.__class__() == '':
#string
elif a.__class__() == []:
#list
But unfortunately in Zope PythonScripts, where I need to use this, one
is not supposed to use underscore-prefixed methods as I just found out.
I figure this is a question general enough to post here (and not on the
Zope list), any clues?
TIA
Jan Kokoska 4 1626
Heyho!
Jan Kokoska wrote:
[...] But unfortunately in Zope PythonScripts, where I need to use this, one is not supposed to use underscore-prefixed methods as I just found out.
In Zope you can use same_type():
same_type(a, '')
same_type(a, [])
(See Zope Book -> Advanced Zope Scripting -> Built-in Functions)
I figure this is a question general enough to post here (and not on the Zope list), any clues?
TIA
Jan Kokoska
HTH,
Wolfram
Jan Kokoska <ko*********@globe.cz> writes: Hello,
I need to recognize 'var' and ['var'], usually I would use:
if a.__class__() == '': #string elif a.__class__() == []: #list
That's a very strange way of doing it in any situation!
Cheers,
mwh
--
This is an off-the-top-of-the-head-and-not-quite-sober suggestion,
so is probably technically laughable. I'll see how embarassed I
feel tomorrow morning. -- Patrick Gosling, ucam.comp.misc
Jan Kokoska <ko*********@globe.cz> writes: I need to recognize 'var' and ['var'], usually I would use:
[...]
All the other solutions posted are bad because they fail for
user-defined string-like classes (unless those classes use the new 2.2
features by deriving from str or unicode). As long as your strings
aren't huge:
def isstringlike(x):
try: x+""
except TypeError: return False
else: return True
I think I stole this off Alex Martelli.
John bo**@oz.net (Bengt Richter) writes: On 05 Dec 2003 20:24:02 +0000, jj*@pobox.com (John J. Lee) wrote:
bo**@oz.net (Bengt Richter) writes: [...] >>> s2 = ['abc','def'][...]> >>> s2 += 'ghi' >>> s2 ['abc', 'def', 'g', 'h', 'i']
That's not what the code I posted tests for.
You mean __iadd__? I know, I was just showing ordinary list behavior, and showed that as well to imply that that's also something you might want to override in a consistent way if you were overriding __add__ as in my example.
What? list.__add__(self, "") raises TypeError, which means lists do
work OK with isstringlike().
[...]
Don't forget, an object's __add__ could be defined to accept _anything_ for addition, and a string would just be a generic thing, whose stringness was really irrelevant to the adding object. Are you making other assumptions based on isstringlike?
That's true: especially given the sequence-ness of strings, which was
the whole motivation for this function in the first place! In fact,
isstringlike(UserList()) is true. Bah.
If so, I think those assumptions should be an explicit part of the test, or you are setting yourself up for using the test and assuming the wrong things about some object. You can say you'll use exceptions will sort those things out,
[...]
Well, sometimes that's just the problem: exceptions *won't* get
raised, because strings are sequences.
I guess it's all depends on the particular case. :-(
John This thread has been closed and replies have been disabled. Please start a new discussion. Similar topics
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