On Fri, 16 Feb 2018 14:18:16 -0800, windhorn wrote about running scripts
from the interpreter:
[...]
> That works, but nothing is very convenient for debugging simple scripts.
> If I run the script from a command prompt it works, but I lose all my
> other stuff (debugging functions, variables, etc.).
I'm sorry, reading your description of the various steps you tried
brought to my mind a chef insisting that the only cooking implement he
needs is a spoon, and then complaining that it's not well suited to
slicing meat :-)
The interactive interpreter, or REPL (Read-Eval-Print Loop) is not
designed for the edit-run-debug-edit cycle. But it can be used as a
single component of that development process.
For me, the tool I use is a set of re-usable tools:
- a text editor;
- a system command prompt in a terminal/console window;
- a Python REPL for running code snippets and looking up help(obj).
Other people prefer a IDE like Spyder (or many others). Either way,
they're designed for the edit-run-debug-edit cycle.
I edit the source code of my script in the text editor, then run it from
the command prompt using
python myscript.py
If I need the debugger, I use:
python -i myscript.py
I often use test driven development, so I have a set of tests written. I
edit the tests, then run the test suite:
python myscript_tests.py
then edit the script to make the tests work.
The best part of this is each time you run the script, it is guaranteed
to be running *fresh*, with no left-over cruft from previous runs.
Trust me, after you've spent hours trying to debug a mysterious problem
in your code, only to discover that it was a side-effect of re-using the
same interactive session that ran an older version of your code, you too
will shudder at the thought of trying to do all your development in an on-
going, persistent REPL session.
> More a comment than a question but seems like sometimes execfile() is
> the right tool.
I'm sure that it is; but the question, the right tool for what?
--
Steve
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