New submission from Forest <fores...@sonic.net>:
When argparse actions have multiple option strings and at least one argument,
the default formatter presents them like this:
-t ARGUMENT, --task ARGUMENT
Perform a task with the given argument.
-p STRING, --print STRING
Print the given string.
By repeating the metavars, the formatter wastes horizontal space, making the
following side-effects more likely:
- The easy-to-read tabular format is undermined by overlapping text columns.
- An action and its description are split apart, onto separate lines.
- Fewer actions can fit on the screen at once.
- The user is presented with extra noise (repeat text) to read through.
I think the DRY principle is worth considering here. Help text would be
cleaner, more compact, and easier to read if formatted like this:
-t, --task ARGUMENT Perform a task with the given argument.
-p, --print STRING Print the given string.
Obviously, actions with especially long option strings or metavars could still
trigger line breaks, but they would be much less common and still easier to
read without the repeat text.
I am aware of ArgumentParser's formatter_class option, but unfortunately, it is
of little help here. Since the default formatter class reserves every stage of
its work as a private implementation detail, I cannot safely subclass it to get
the behavior I want. My choices are apparently to either re-implement an
unreasonably large swath of its code in my own formatter class, or override the
private _format_action_invocation() method in a subclass and risk future
breakage (and still have to re-implement more code than is reasonable.)
Would it make sense to give HelpFormatter a "don't repeat yourself" option?
(For example, a boolean class attribute could be overridden by a subclass and
would be a small change to the existing code.)
Alternatively, if nobody is attached to the current behavior, would it make
sense to simply change HelpFormatter such that it never repeats itself?
----------
components: Library (Lib)
messages: 401110
nosy: forest
priority: normal
severity: normal
status: open
title: argparse repeats itself when formatting help metavars
type: behavior
versions: Python 3.10, Python 3.11, Python 3.6, Python 3.7, Python 3.8, Python
3.9
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Python tracker <rep...@bugs.python.org>
<https://bugs.python.org/issue45110>
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