Nope, that isn't right either, in the sense that it handles all the
cases properly, including "single string" vs "list of strings'. Guess
this overly simplistic aslist() does not work after. I should have been
more suspicious and cautious before posting. Sorry.
Martin
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Ooops. I left out an "*" on a statement in the new aslist() function. I
should have written:
def aslist(*args):
return list(*args) # corrected
def f(arg):
args = aslist(arg)
...
Sorry,
Martin
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http://mail.python.org/mailman/listinfo/python-list
At the end of his last post, Steve Bethard wrote:
> That said, I find that in most cases, the better option is to use
*args
> in the original function though. For example:
>
> def f(arg):
> args = aslist(arg)
> ...
> f(42)
> f(['spam', 'eggs', 'ham'])
>
> could pro
"Steven Bethard" <[EMAIL PROTECTED]> wrote in message
news:[EMAIL PROTECTED]
> I don't like this idea much because it depends on str and unicode _not_
> having a particular function. I haven't seen any guarantee anywhere that
> str or unicode won't ever grow an __iter__ method. So this code s
Martin Miller broke the order of reading again by top-posting:
However, to handle the more general problem of allow *any* argument to
be either a single item or a list seems to require a combination of
both EAPF and LBYL. This is the best solution I've been able to come up
with so far:
def asList(a
Testing for the '__iter__' (or even '__getitem__') attribute doesn't
really address the problem, nor does trying to execute the statement
'itr = iter(a)'.
To use EAPF and answer the OP's original question, which was
> So how can I test if a variable 'a' is either a single character
> string or a
> Steven Bethard wrote:
>>
>>Right. str and unicode objects support iteration through the old
>>__getitem__ protocol, not the __iter__ protocol. If you want to use
>>something as an iterable, just use it and catch the exception:
>>
>>try:
>> itr = iter(a)
>>except TypeError:
>> # 'a' is n
Yes, both string and lists have a __getitem__ attribute:
>>> c1 = 'abc'
>>> c2 = ['de', 'fgh', 'ijkl']
>>> hasattr(c1, '__getitem__')
True
>>> hasattr(c2, '__getitem__')
True
In other words you could index elements of either one using [].
Likewise, both a string and list would produce a usable i
Terry Hancock wrote:
> But you probably shouldn't do that. You should probably just test to
> see if the object is iterable --- does it have an __iter__ method?
>
> Which might look like this:
>
> if hasattr(a, '__iter__'):
> print "'a' quacks like a duck"
Martin Miller top-posted:
I don't beli
I don't believe you can use the test for a __iter__ attribute in this
case, for the following reason:
>>> c1 = 'abc'
>>> c2 = ['de', 'fgh', 'ijkl']
>>> hasattr(c1, '__iter__')
False
>>> hasattr(c2, '__iter__')
True
>>> for i in c1: print "i=%s is an element of c1" % repr(i)
...
i='a' is an element
On Wednesday 16 February 2005 09:08 am, alex wrote:
> how can I check if a variable is a structure (i.e. a list)? For my
> special problem the variable is either a character string OR a list of
> character strings line ['word1', 'word2',...]
>
> So how can I test if a variable 'a' is either a sing
alex wrote On 17/02/05 02:08:
how can I check if a variable is a structure (i.e. a list)? For my
special problem the variable is either a character string OR a list
of character strings line ['word1', 'word2',...]
You're trying to apply the LBYL principle. My bet is that your "special
problem" c
Michael Hartl wrote:
I use a function isListLike in cases such as this one:
# def isListLike(L):
# """Return True if L is list-like, False otherwise."""
# try:
# L + []
# return True
# except:
# return False
Then you can use a standard if-else construct:
# if isL
I use a function isListLike in cases such as this one:
# def isListLike(L):
# """Return True if L is list-like, False otherwise."""
# try:
# L + []
# return True
# except:
# return False
Then you can use a standard if-else construct:
# if isListLike(myvar):
#
alex wrote:
So how can I test if a variable 'a' is either a single character string
or a list?
py> def test(x):
... return (isinstance(x, list) or
... isinstance(x, basestring) and len(x) == 1)
...
py> test('a')
True
py> test('ab')
False
py> test([])
True
py> test(['a', 'b'])
True
B
import types
v = []
if type(v) is types.ListType:
pass
--
Regards,
Diez B. Roggisch
--
http://mail.python.org/mailman/listinfo/python-list
Perhaps you're looking for the type() built in function and the types modules?
>>> type('aaa')
>>> type([])
>>> import types
>>> if type([]) is types.ListType:
... print 'is a list'
...
is a list
Chris
On Wed, 16 Feb 2005 07:10:56 -0800 (PST), alex
<[EMAIL PROTECTED]> wrote:
> Hi ther
On Wed, 16 Feb 2005 07:11:08 -0800 (PST), alex
<[EMAIL PROTECTED]> wrote:
> how can I check if a variable is a structure (i.e. a list)? For my
> special problem the variable is either a character string OR a list of
> character strings line ['word1', 'word2',...]
>
> So how can I test if a variabl
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