[Python-Dev] Alternative path suggestion

[Nick Coghlan]

Mike Orr wrote:
> I think you meant to say Perl in that sentence.  In Python there
> should be one way to do it, and beautiful is better than ugly.  The
> os.path functions are bad enough, but shutil.copy2 is just plain evil.

I agree a decent pathlib may make many of the low-level filesystem 
manipulation modules obsolete - just not necessarily all of them. Until we get 
an actual module to experiment with, we won't really know.

>   Is it that much of a step to translate:
> 
>    Y="$(dirname $(dirname $X))/lib"
> 
> as
> 
>    y = Path(x).parent.parent + "lib"
>    y = Path(x).parent.parent.join("lib")
>    or whatever the syntax do jour is

I'd suggest something like:

y = Path(x).parent(2) + "lib/"

Where the parent function works like (based on the three-part internal data 
approach I posted recently):

   def parent(self, generation=1):
       return type(self).from_parts(
                         self.basepath, self.dirparts[:-generation], ())

And path addition is equivalent to:

   def __add__(self, other):
       if isinstance(other, basestring):
           other = Path(other)
       if self.nameparts:
           raise ValueError("Cannot add to path with non-empty name")
       if other.basepath:
           raise ValueError("Cannot append non-relative path")
       dirparts = self.dirparts + other.dirparts
       return type(self).from_parts(
                     self.basepath, dirparts, other.nameparts)


Anyway, I'll try to find some time to look at this on the Wiki. It'll be 
easier to bat code back and forth over there.

Cheers,
Nick.

-- 
Nick Coghlan   |   ncoghlan at gmail.com   |   Brisbane, Australia
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