Re: [RFC] Re: Convert 'git blame' to parse_options()

[Linus Torvalds <torvalds@linux-foundation.org>]

On Mon, 23 Jun 2008, Linus Torvalds wrote:
> 
> Trust me, you need what I wrote. Something that parses all the options in 
> one go, and ignores the ones it cannot parse, because a TOTALLY DIFFERENT 
> function than the caller will call it!

Side note: of course you can always just queue them up yourself, and then 
pass those off to the later stage. But where do you queue them? Can you 
re-use argv[]? If so, what's the difference with the simpler patch that I 
already posted? (simpler both from a usage standpoint _and_ from a patch 
size standpoint).

That said, I *really* don't care what the end result is, but I would 
strongly urge people to actually look at what existing code does. That 
includes at a minimum builtin-blame.c, but also all the existing users 
where _most_ of the arguments are just trivial. builtin-apply.c is a great 
example of something where it's almost all trivial, but a lot of the 
options set more than one value.

The guiding light here should not be how pretty or clean option-parse.c 
is, but how easy it is to convert the hundreds of existing options that 
haven't been converted yet. And a lot of them haven't been converted 
because it's currently very painful to do multi-valued things, even if 
most of those values really are pretty simple.

In that vein - maybe it would be a good idea to allow multiples of the 
same option, so that things like builtin-apply.c can handle the "-p" 
option (to give an example of this behaviour) as a set of TWO options that 
do

	OPT_INTEGER('p', NULL, &p_value, "Patch depth"),
	OPT_BOOLEAN('p', NULL, &p_value_known),

where "-p3" would then trigger on both, once setting "p_value" to 3, and 
once setting p_value_known to 1.

I dunno. But _this_ is the real problem with parse-options.c. It's hard to 
convert existing really simple parsers. Whether the problem is writing a 
sane set of rules for it without using callbacks (callbacks are neither 
easy nor clean), or whether the problem is that the parsing is done in 
multiple different places..

			Linus