os.path and Path

[Steven D'Aprano]

On Wed, 15 Jun 2011 19:00:07 -0700, Ethan Furman wrote:

> Thread 1: "objects of different types compare unequal" self:    
> "nonsense!  we have the power to say what happens in __eq__!"
> 
> Thread 2: "objects that __hash__ the same *must* compare __eq__!" self: 
>    "um, what? ... wait, only immutable objects hash..."

Incorrect. And impossible. There are only a fixed number of hash values 
(2**31 I believe...) and a potentially infinite number of unique, unequal 
objects that can be hashed. So by the pigeon-hole principle, there must 
be at least one pigeon-hole (the hash value) containing two or more 
pigeons (unequal objects).

For example:

>>> hash(2**0 + 3)
4
>>> hash(2**64 + 3)
4


What you mean to say is that if objects compare equal, they must hash the 
same. Not the other way around.


> Thread 2: "you're Path object is immutable..." self:     "argh!"
> 
> Here's the rub:  I'm on Windows (yes, pity me...) but I prefer the
> unices, so I'd like to have / seperate my paths.  But I'm on Windows...

Any sensible Path object should accept path components in a form 
independent of the path separator, and only care about the separator when 
converting to and from strings.


[...] 
> So, I suppose I shall have to let go of my dreams of
> 
> --> Path('/some/path/and/file') == '\\some\\path\\and\\file'

To say nothing of:

Path('a/b/c/../d') == './a/b/d'


Why do you think there's no Path object in the standard library? *wink*



-- 
Steven