Albert Hopkins wrote:
On Thu, 2009-03-19 at 11:57 -0500, Jim Garrison wrote:
Use case: parsing a simple config file line where lines start with a
keyword and have optional arguments. I want to extract the keyword and
then pass the rest of the line to a function to process it. An obvious
use of split(None,1)
cmd,args= = line.split(None,1);
if cmd in self.switch: self.switch[cmd](self,args)
else: self.errors.append("unrecognized keyword '{0)'".format(cmd))
Here's a test in IDLE:
>>> a="now is the time"
>>> x,y=a.split(None,1)
>>> x
'now'
>>> y
'is the time'
However, if the optional argument string is missing:
>>> a="now"
>>> x,y=a.split(None,1)
Traceback (most recent call last):
File "<pyshell#42>", line 1, in <module>
x,y=a.split(None,1)
ValueError: need more than 1 value to unpack
I understand the problem is not with split() but with the assignment
to a tuple. Is there a way to get the assignment to default the
missing values to None?
why not do this?
>>> a= 'now'
>>> z = a.split(None, 1)
>>> x = z[0]
>>> y = z[1] if len(z) == 2 else None
A 1-line solution (not necessarily recommended) is:
x, y = (a.split(None, 1) + [None])[ : 2]
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