On 26Aug2017 21:27, boB Stepp <robertvst...@gmail.com> wrote:
I have a project structure where I am developing various programs,
some in Pinnacle HotScript language, some in Perl, some in Python,
some shell scripts. For the purpose of this question, my simplified
development file structure is:
~/_dev_Scripts
/ScriptMenuSystem
__init__.py
test.py
/py_utilities
__init__.py
test.py
When I am fully happy (Not really! ~(:>)) ) with everything I will
copy everything pertinent from "~_dev_Scripts" into a location like
"/usr/local/.../Scripts/boB_Scripts". So all code must be able to
handle any change in location from where I am developing it. On to my
difficulties ...
ScriptMenuSystem/test.py:
-------------------------------------------------
#!/usr/bin/env python
import sys
sys.path.append('..')
import py_utilities.test as t
t.test_print()
The trouble with this specific approach is that '..' relies on your _working_
directory being above ScriptMenuSystem i.e. the directory you shell's in; '..'
is not related to the path to the test.py file. What yu want for this is the
actual path to the code i.e. __file__. Eg:
sys.path.append(dirname(dirname(__file__)))
but that requires your module to know its own location within your library i.e.
that it is .../dev_scripts/ScriptMenuSystem/test.py, and therefore that you
want .../dev_scripts. Fragile. (And __file__ doesn't work in some more arcane
ways of distributing modules, such as in zip files but let's not go there, not
least because I've never done that myself).
The usual approach is to burden the user of the module. They're using it:
ideally they have "installed" it by putting it somewhere sensible. So in a
sense you should be able to rely on $PYTHONPATH already being set up.
Think about the end game: supposing people are using your modules in some
larger system (eg a virtualenv). Do they really even _want_ you mucking about
with their $PYTHONPATH or sys.path or, really, anything that will affect how
modules are looked up?
Personally, I rely on $PYTHONPATH being right when I'm called. If someone's
"installed" your module (eg by putting it in site-packages or wherever) the
path is already set up. For my development purposes I invoke my code via a
"dev" shell function which prehacks $PYTHONPATH to have my local lib directory
at the start of $PYTHONPATH. Again, the module itself can then trust that
things are as they should be. Which is as it should be.
Cheers,
Cameron Simpson <c...@cskk.id.au> (formerly c...@zip.com.au)
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