[Python-Dev] Relative Package Imports

[Jim Fulton]

"M.-A. Lemburg" wrote:
> 
> James C. Ahlstrom wrote:
> >
> > First, I am not all that opposed to having a notion of ".."
> > available in the import statement.  If we can write zope.dir1.mod1
> > which is a relative import going down, maybe we can write
> > ../dir2/mod2 or something spelled differently.  But I think
> > there would still be problems.
> >
> > We would be relying on all package authors to use ".."
> > or "__" within their package.  But it is more natural to write
> > zope.this.that or mx.this.that everywhere, and that is what
> > people have in fact done.  Probably there would be bugs and
> > at least annoyance.
> 
> Think of it as an opportunity: it makes intra-package imports
> very simple without hard-wiring paths to submodules
> into the package.
> 
> In the end, having written a self-contained package is a "feature"
> of that package. Other authors can then say: ok, I can
> plugin your package if it's self-contained.

Well said.  It really should be possible to provide
*self-contained* package hierarchies.

> I have a feeling that this discussion is loosing its grip
> on reality a bit. Jim and I are not argueing to change
> Python's face, internal structure or look&feel. The '__' thing
> doesn't harm anyone, doesn't break any functionality or
> code. It is even now already possible using import hooks and
> has been implemented before in ni.py using just that technology.
> 
> All that we are talking about is reviving relative imports
> so that its usage is possible *without* adding yet another
> hook. This is not about the pros and cons of deeply nested
> packages and neither about advantages of shallow structures.
> Its only about adding semantics to the string '__' used
> in import statements. Nothing more. People are not forced
> to use it. Besides, if used it will be a package internal
> technique and not be visible to users of that package.
> 
> Now why would anyone want to make life harder for package
> authors ?

I don't think nearly enough Python code has
been packagized.  Packages are critcal for large projects
and for reuse of code within large projects.  There are at 
least two people in this discussion that are trying hard to
make use of packages and have observed a significant problem.
If we really want to encourage developers of reusable Python
software to use packages, then I think it would be wise to pay
attention to people who are actively using packages and have
encountered problems.

Jim

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