Re: [gentoo-dev] Parsable list of all use variables.

[Bob Phan]

On Sun, 12 May 2002, Karl Trygve Kalleberg wrote:

> On Fri, 10 May 2002, Bob Phan wrote:
>
<snip>
> >
> > voodoo3 - Adds support for 3Dfx's Voodoo3 video chipset, else
> >           defaults to Voodoo4/5 support if not in USE
> >
<snip>
>
> This regex handles those cases:
>
> ^([a-z0-9]+)[ \t]+-.*
>
The problem with that regex is it only strips out the use variables.
I was doing something similar before.  But I wanted to be able to
easily parse out all the information in that file.

> > I've already written a script that can mine out all optional use
> > statements.  Adding the functionality to dynamically go backwards
> > through the dependancy tree would be trivial.
> >
> > I just wanted to get a sense from all of you out there as to what you
> > would vote for as a better standard for keeping a separate list with
> > this information, which I or anyone can maintain.  It would be really
> > useful for a few scripts I've been meaning to write, such as a GTK+
> > based auto USE var generator.  And a "what options are available to me
> > in this ebuild before I install it" script.  I'm also sure others
> > would find some use for such information to be stored in a more usable
> > format.
>
> I used to think the format should be changed. If the use.desc file is
> supposed to be only machine-readable, it certainly should be changed.
>
> However, if users are supposed to read that file as well, we should not
> change it, as it is currently easy enough to parse and extremely easy
> to read.

I wouldn't suggest making it any harder to read.  Avoiding newlines
midrecord wouldn't make reading it much more difficult.  Especially if
empty lines were permitted.  And I liked Georges idea of splitting
each line into two parts, use-var<whitespace>description<newline>.
Where any whitespace minus newline would be permitted to split the use
var from the description.

> There are currently 255 out of 2959 ebuilds that use undocumented use
> flags. These use flags will have to be moved into use.desc.
>
> There has been discussion of an IUSE var for each ebuild, that lists the
> use flags that an ebuild can avail itself of. This would ease up the task
> of collectiong these options. In the meantime, the regex
>
> [^#]*use ([a-z0-9]+).*
>
> does the trick.

I was previously parsing that info out of the DEPEND and RDEPEND,
grabbing /\?\w+/ for the use vars, but your regex is more elegant.
I'll update my script to use that.

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