Non IDE development strategy - what do others do that's fairly simple?

[Chris Green]

I have a few python programs that I have written which I need to do
some fairly extensive changes to (to get from gtk to gobject and to
move to Python 3).  This is on a Linux (xubuntu 20.04) system.  I use
the command line to do just about everything (even though the program
is GUI!) and so I tend to edit in one window and test in an adjacent
window on the same screen, I don't find GUI development environments
comfortable.

The existing code simply lives in ~/bin with a couple of modules in
~/bin/pymods (which directory is in my PYTHONPATH).

I use mercurial for configuration management of the code, directly in
the ~/bin directory.  This works fine for the sort of minor bug fixing
and updates that I do most of the time, I'm the only user so changing
the 'live' code isn't a major issue and I can always drop back to the
last working version using mercurial.


However with this more major change to do I really need a
'development' copy of the code as well as the live working copy as
it's likely I will take a few days to do the changes (as in an hour or
so each day over some days) and I need the ability to use the program
meanwhile.


So, finally to the question, does anyone else have this command line
based sort of approach and, if so, what do they do to provide a
'development version' of a program in parallel with a working version?

I guess virtualenv (Python 2) and venv (Python 3) address this problem
but they do feel rather more complex than I actually need and I'm not
very clear how you move code from the virtual environment to 'live'.
There's also the issue that I'm moving code from Python 2 to Python 3
so which virtual environment should I use?

Any ideas or suggestions would be very welcome.

-- 
Chris Green
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