[Pythonmac-SIG] Building plans .....

[Christopher Barker]

On Mon, Mar 16, 2020 at 3:55 PM Jack Jansen <jack.jansen at cwi.nl> wrote:

but "conda" is a package management tool, a bit like yum or apt in the
Linux world, or Brew, for that matter. except that:

* It provides management of isolated "environments", so you can have a
different collection of software and libraries, all with a different
combination of version on the same system, isolated from one another.

So how does conda handle things that must be installed in “special”
> locations on some platforms? For example, if you install some package that
> contains a kernel driver, undoubtedly on windows this’ll have to go
> somewhere deep down in c:\system32 or something.
>

I expect that answer is "it doesn't" -- it's really not intended to support
things like kernel drivers. The point of conda is not just package
management, but  the ability to create isolated environments, with specific
versions of various inter-dependent packages.

An environment is essentially a directory tree with a loto f familiar (to
the *nix folks, anyway) directories. Here's what's in my primary working
environment, for example:
$ ls
bin                                phrasebooks
conda-meta                         plugins
doc                                qml
etc                                qsci
include                            resources
lib                                sbin
libexec                            share
man                                ssl
mkspecs                            translations

When you "activate" an environment, it sets up a bunch of environment
variables so that those "Versions" are found first. Here's $PATH by my
primarily working environment (called py3) is activated:

$ echo $PATH
/Users/chris.barker/miniconda3/envs/py3/bin:/Library/TeX/texbin:/Users/chris.barker/miniconda3/condabin:/usr/local/bin:/usr/bin:/bin:/usr/sbin:/sbin:/usr/local/sbin

It prepended the bin dir from the Environment on there. It does similar
things to all the other env variables.

Because in a way Python on the mac (if you want to use a
> framework/app/bundle Python) is like that: it has some platform-specific
> installation requirements (that bits of it go into /Library/Frameworks and
> other bits in /Application), and in the end you setup a few symlinks in the
> conda bin directory (or the conda per-environment bin directory, or however
> that works) and for a conda user the situation will be exactly the same on
> Mac as on Linux…..
>

So yes, you could install the entire Framework inside the environment, and
then have the various links to the "expected" places inside that
environment (conda uses relative paths wherever possible, so it wouldn't be
hard). And probably, it would end up looking just like a *nux install as
far as everything else is concerned, except for that extra Framework thing
in there somewhere that could be ignored.

I'm not sure why the conda folks decided not to do that in the first place,
but they didn't, and no one seems to want to do it now.

I suppose I could set it up and submit a PR and see what folks think, but
the big question is: what does a Framework Build by conda? ANd I think the
answer is nothing, except that we already know how to build the pythonw
executable that way.

-Chris
-- 
Christopher Barker, PhD

Python Language Consulting
  - Teaching
  - Scientific Software Development
  - Desktop GUI and Web Development
  - wxPython, numpy, scipy, Cython
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