In argparse, I've always wanted a way to make colored help text like those of poetry and pipenv. But argparse's show help isn't well documented (Therefore, I can't find a way to completely modify the help text), and the metavar arg isn't really helpful. I want to do something like this:

>>> import argparse
>>> parser = argparse.ArgumentParser()
>>> parser.add_argument("foo", help="To foo a bar", display="FOO!!!!")
>>> parser.print_help()

usage: main.py [-h] foo

positional arguments:
  FOO!!!!     To foo a bar

optional arguments:
  -h, --help  show this help message and exit

>>>

That way, I can colorize the help output.

> and the metavar arg isn't really helpful.

Is your issue with *metavar* that it changes the help() output in two places?

I'm not following this request either, especially the colored part.

However, I can imagine adding a variable that gives the user full control over the action-invocation.  In:

    argparse.HelpFormatter._format_action_invocation method.

Currently it accepts the metavar (but not the tuple version) for a positional, but for optionals constructs:

  -s ARGS, --long ARGS

This can be quite long and ugly if the ARGS is a long choices, or there are many flag alternatives.  A number of SO users have asked for something simpler, usually with just on flag or

  -s, --long ARGS

There may even be a bug/issue(s) related to this already.

>However, I can imagine adding a variable that gives the user full control over the action-invocation.  In:

    argparse.HelpFormatter._format_action_invocation method.

That's what I'm trying to change. If there was a public API/method for manipulating the left side of the help menu.

  (This part)     (Manipulatable via help=)

That method could be customized in a HelpFormatter subclass.  There already are several subclasses (documented), and writing your own is allowed, if not actually encouraged.

https://docs.python.org/3/library/argparse.html#formatter-class

Adding an extra parameter to 'add_argument', and passing that on through the Action class (and subclasses) is, potentially, a bigger task.  

So if you can get by with just customizing _format_action_invocation, there's no need for further action here.

I'll look for some examples, here or on SO, of customizing this method.

Should I rename this to "Argparse: finer control on help txt"

> So if you can get by with just customizing _format_action_invocation, there's no need for further action here.

Then maybe we could just make a new function that takes 2 arguments: Name of another action class (or the action class itself), and a tuple of the arg names to be displayed. It returns a new action class that contains the help text properties of the given action class with customized displayed arg names.


Maybe like

parser.add_argument("-f", "--foo", action=argparse.CustomArgName(action="store_true", name=("-F!!", "--FOO!"), help="TO foo a bar"))

Some StackOverFlow answers cusomizing this help method:

https://stackoverflow.com/questions/23936145/python-argparse-help-message-disable-metavar-for-short-options

https://stackoverflow.com/questions/18275023/dont-show-long-options-twice-in-print-help-from-argparse

Editing the description, etc. seems like a good way to do this. But it seems "hacky". The other answer on StackOverflow implements a custom class which does nice things, but not what I want.

In the end, I think python's argparse needs more built-in help formatters...


Should I close this?