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
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