Re: optional argument?

[Tanaka Akira <akr@xxxxxxxx>]

In article <200005080944.LAA15834@xxxxxxxxxxxxxxxxxxxxxxxxxxxx>,
  Sven Wischnowsky <wischnow@xxxxxxxxxxxxxxxxxxxxxxx> writes:

> Well, in this case it is really caused by --context not accepting its
> argument in a separate word.

Yes.  So, I used `--context=-' in _cvs for `cvs diff'.  However this
is bit annoying because `=' is not removal suffix.

> Hm, what are we supposed to do now? Generally making it not complete
> normal arguments when in a position for an optional option-argument
> wouldn't solve the problem. Making it not complete optional option-
> arguments in separate words could be wrong, too, for commands that can 
> find out if the argument is a normal or for the option.

Actual commands which has optional arguments judge whether they are
specified or not in a some criteria.  So, supporting some common
criteria is useful.

> Hrmpf. Make `='-options complete the argument *only* after the equal
> sign? Add a new specification type, say `-opt==' for options that
> don't accept the argument in a separte word (should the long-option
> auto-detection code use it then?)?

Exactly, the existence of `=' is the criteria used by getopt_long.  So
it's good.  But I vote `-opt=?' instead of `-opt=='.

Note that another common criteria is that a optional argument must be
some set of strings: `yes' or `no' for example.  At least, xset
handles optional arguments in this way.  If we can specify a pattern
addition to the current optional argument syntax, it can be handled.
However, _xset cannot use _arguments since it has more anomalies if
the optional arguments can be handled.

Apart from that, I hope a extension for _arguments.  There are 
many duplicated descriptions such as:

    ....
    '(-i)--ignore-case[case insensitive]' \
    '(--ignore-case)-i[case insensitive]' \
    '(-w)--ignore-all-space[ignore all white space]' \
    '(--ignore-all-space)-w[ignore all white space]' \
    '(-b)--ignore-space-change[ignore changes in the amount of white space]' \
    '(--ignore-space-change)-b[ignore changes in the amount of white space]' \
    '(-B)--ignore-blank-lines[ignore lines that are all blank]' \
    '(--ignore-blank-lines)-B[ignore lines that are all blank]' \
    '(-I)--ignore-matching-lines=[ignore lines that match regex]:line exclusion regex:' \
    '(--ignore-matching-lines)-I+[ignore lines that match regex]:line exclusion regex:' \
    ...

So, I really want to describe them as:

    ...
    '--ignore-case,-i[case insensitive]' \
    '--ignore-all-space,-w[ignore all white space]' \
    '--ignore-space-change,-b[ignore changes in the amount of white space]' \
    '--ignore-blank-lines,-B[ignore lines that are all blank]' \
    '--ignore-matching-lines=,-I+[ignore lines that match regex]:line exclusion regex:' \
    ...

In other words, I think it is useful that opt-spec is comma separated
list of options.  And exclusive options are automatically set up each
other if they are not prefixed as `*'.
-- 
Tanaka Akira