[Distutils] eggs in Python path

[Jim Fulton]

Phillip J. Eby wrote:
> At 10:46 AM 1/15/2006 -0500, Jim Fulton wrote:
> 
>> The eggs quick guide 
>> http://peak.telecommunity.com/DevCenter/PythonEggs#using-eggs
>> says that eggs can be installed by just putting them on sys.path.  
>> This doesn't
>> seem to be enough though. A .pth file seem to also be necessary.
>>
>> Am I missing something?
> 
> 
> Two somethings.  :)
> 
> First, you *can* install an egg by putting it on sys.path.  A .pth file 
> is just one *way* of putting it on sys.path.

Ah

> What you're asking about is installing an egg by putting it *in a 
> directory that's on sys.path*, which is a different thing.  You can also 
> do this, as long as you're using the pkg_resources API to request the 
> egg, or it's one of your requirements specified by your egg.
> 
> The only egg that absolutely *must* be in a .pth (or otherwise get onto 
> sys.path) is the setuptools egg.  As long as that's the case, then it is 
> not necessary to have .pth files, because the act of require()-ing an 
> egg will cause it and all its dependencies to be added.

Sure, but then you have to call require. :)

> 
>> Or is the documentation incorrect?
> 
> 
> It might be a bit confusing about this issue, but I've so far found that 
> changing it around doesn't help much.  :(  This is simply something so 
> new to most people that they seem to project their existing thought 
> process onto it no matter what it actually says, and then only get it 
> after bumping into a problem or mental contradiction.  If you think you 
> can improve upon the comprehensibility without making it so complex that 
> nobody will read it anyway, feel free to submit a patch.  :)

I think that a sentance or 2 saying that when you talk about putting an egg
on sys.path or in PYTHONPATH you mean putting the path to the egg file in
the list of paths.  I suggest that:

"If you have a pure-Python egg that doesn't use any in-package data files,
  and you don't mind manually including the path to the egg file in sys.path
  or in PYTHONPATH, you can use the egg without installing setuptools.
"

Would be much clearer.

The original text talks about putting the *egg* *on* sys.path or PYTHONPATH.
This is missleading in 2 ways:

1. You aren't putting the egg anywhere.  You are putting the name of the egg
    somewhere.

2. When we talk about putting something "on" a path, that suggests (at least to me)
    that you'll be able to find it in one of the directories specified in the path.

Jim

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