Steven Bethard schrieb:
> On Sun, Apr 18, 2010 at 3:31 AM, Tobias Herp <tobias.h...@gmx.de> wrote:
>> To put it short:
>> *Argparse should simply do this like optparse does already.*
>> I.e., use '--version', '--help' and '-h' by default, but not '-v'.
> [snip]
>> What happened was the following:
>> Completely unnecessarily, the 'version' constructor argument is now
>> deprecated.
> [snip]
>> The deprecation of the 'version' argument press-gangs people to replace
>> it by
>> parser.add_argument('--version', action='version',
>> version='<the version>', # the only common part
>> help="show program's version number and exit")
>
> What Tobias has conveniently omitted is that there was not much
> agreement on what the default behavior of the version flag should be.
Well, the mail was quite long already, and the issue-tracker issue was
linked.
> Things that were proposed:
>
> * Use both -v and --version
This is very unusual. I don't know of a single example other than
existing argparse. Incompatible to existing optparse usage.
> * Use both -V and --version
A very common combination; many programs which support --version
accompany it with -V.
However, if we'd add '-V' to the default option strings, we would likely
break existing programs which worked around the so-far default.
> * Use just --version
IMO the only way, and the way optparse does it.
> * Print out just the version string
> * Print out program name with the version string
If this is an issue: With optparse, the version argument value is
printed, which is often something like '%prog '+VERSION
(for argparse, '%(prog)s '+VERSION or '%%(prog)s %s' % VERSION).
This way, the decision is left to the programmer.
Completely agreeable, as far as I'm concerned.
> I put up a poll [...]
>
> Given the lack of consensus, the many
> different options people thought were the "right" way to do things,
> and the fact that the action='version' approach allows people to
> customize the flags to whatever they want, I stick by my decision to
> deprecate the constructor argument ...
A. Very. Bad. Idea.
> ... and redirect people to the more flexible add_argument approach.
It is ok to /allow/ people to customize the flags to whatever they want.
It is /not/ ok to /force/ them to do so, if there is a perfectly
reasonable solution which allows them to stick with their habits.
And there is one: drop the '-v' default. The only way (see above).
> In the face of ambiguity, refuse the temptation to guess.
No guessing is needed (and the ZoP aphorism is not applicable here: this
is not about guessing what the user might have meant. Besides, if the
user specifies '--version', [s]he /very/ likely wants some info about
the program version; giving '-v' can have been done looking forward to
--verbose output (ok, nothing bad will happen, but it mismatches user
expectations).
> In general, I should say that I'm not opposed to changing the behavior
> in Python trunk, even if it causes a bit of backwards incompatibility.
A /very little/ bit.
When fetching stdout to get the program version, it is much more
reasonable to rely on '--version' than on '-v'. This is /the/ option
string which is best supported by far.
> But I'd really like a consensus about the correct behavior, and so far
> I have not seen that.
We'll have one ;-)
--
Tobias
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