Subject: Re: bug#19219: Package names with digits following dashes

From: [email-masked] (Ludovic Courtès)
Date: Mon, 21 Dec 2015 22:46:30 +0100

Mathieu Lirzin <[email-masked]> skribis:

> The test case contains the example "guile-2.0.6.65-134c9" which
> invalidates my proposal.  Here is another idea which identifies the
> version part by the presence of dots.  WDYT?

Sometimes the version part does not contain dots, as in “diffoscope-34”.
Here’s the complete list of dot-less versions:

--8<---------------cut here---------------start------------->8---
scheme@(guile-user)> ,use(gnu packages)
scheme@(guile-user)> (fold-packages (lambda (p r)
				      (if (string-index (package-version p) #\.)
					  r
					  (cons (package-full-name p) r)))
				    '())
$38 = ("xterm-320" "unclutter-8" "tidy-20091223" "perl-uri-find-20140709" "libx264-20150706-2245" "vapoursynth-28" "texlive-texmf-2015" "texlive-bin-2015" "texlive-2015" "scmutils-20140302" "perl-regexp-common-2013031301" "parallel-20151122" "diffoscope-34" "mg-20050429" "ngircd-22" "bootstrap-tarballs-0" "static-binaries-tarball-0" "usbutils-006" "kmod-17" "less-481" "libjpeg-9a" "libjpeg-8d" "hugs-Sep2006" "ghc-bifunctors-5" "ghc-nats-1" "brdf-explorer-17" "libgudev-230" "psutils-17" "gcal-4" "libspiro-20071029" "fontforge-20120731-b" "font-gnu-freefont-ttf-20100919" "pcb-20140316" "paredit-24" "sfarkxtc-b5e0a2ba39" "lz4-131" "ld-wrapper-0" "glibc-bootstrap-0" "gcc-bootstrap-0" "binutils-bootstrap-0" "bootstrap-binaries-0" "bless-1p02" "tzdata-2015c" "freepats-20060219" "acpica-20150410")
--8<---------------cut here---------------end--------------->8---

Would they still be suitably parsed?

I liked that the initial algorithm was trivial, as in Nix:

--8<---------------cut here---------------start------------->8---
/* Parse a derivation name.  The `name' part of a derivation name is
   everything up to but not including the first dash *not* followed by
   a letter.  The `version' part is the rest (excluding the separating
   dash).  E.g., `apache-httpd-2.0.48' is parsed to (`apache-httpd',
   '2.0.48'). */
DrvName::DrvName(const string & s) : hits(0)
{
    name = fullName = s;
    for (unsigned int i = 0; i < s.size(); ++i) {
        /* !!! isalpha/isdigit are affected by the locale. */
        if (s[i] == '-' && i + 1 < s.size() && !isalpha(s[i + 1])) {
            name = string(s, 0, i);
            version = string(s, i + 1);
            break;
        }
    }
}
--8<---------------cut here---------------end--------------->8---

Another option would be to return a list of possible name version pairs,
and to change the UI to try them one after another?  The downside would
be that it moves complexity to the UI.  Hmm…

Ludo’.