Need alternate floating point version comparison function for perl5 portgroup ports

[vinc17@…]

"port outdated" doesn't list p5-xml-libxml, though the latest version isn't installed:

prunille:~> port outdated
The following installed ports are outdated:
goffice                        0.3.5_0 < 0.3.8_0         
pango                          1.16.2_0 < 1.16.4_0       
sqlite3                        3.3.16_0 < 3.3.17_0       
wormux                         0.8alpha1_0 < 0.7.9_0
prunille:~> port installed p5-xml-libxml
The following ports are currently installed:
  p5-xml-libxml @1.62001_0 (active)
prunille:~> port list p5-xml-libxml
p5-xml-libxml                  @1.63           perl/p5-xml-libxml
p5-xml-libxml                  @1.62001        perl/p5-xml-libxml
prunille:~> port info p5-xml-libxml
Warning: Found 2 port p5-xml-libxml definitions, displaying first one.
p5-xml-libxml 1.63, perl/p5-xml-libxml (Variants: universal)
http://search.cpan.org/~msergeant/XML-LibXML-1.63/
[...]

and the primary PortIndex file says that the version is 1.63.

I wonder if "port outdated" doesn't list p5-xml-libxml because 62001 > 63. Instead, the comparison should be done on floating-point numbers 1.63 and 1.62001 (AFAIK, this is the rule for Perl).

[eridius@…]

You sure it's not because you have 2 entries for p5-xml-libxml?

Which begs the question... why do you have 2 entries for p5-xml-libxml? There's only 1 in the dports tree.

[vinc17@…]

I have 2 entries (one from the SVN working copy and one from rsync[*]), but as shown by "port list", version 1.63 has the precedence.

[*] My /opt/local/etc/ports/sources.conf file contains:

file:///Users/vinc17/wd/macosx/dports
file:///Users/vinc17/software/dports
rsync://rsync.macports.org/dpupdate/dports

[vinc17@…]

"port -v outdated" says:

p5-xml-libxml                  1.62001_0 > 1.63_0       !

[eridius@…]

You're right. Our version comparison function is seeing 62001 > 63. The easiest fix is to throw an epoch value on the Portfile, which is basically a timestamp. I don't see any way to teach the version comparison function to do this one "right" without breaking other comparisons like 1.10_0 > 1.9_0.

[boeyms@…]

There's a function currently in glibc called strverscmp() that would get this right. I've been working on a make-alike implementation that can be released on less restrictive terms than the GPL (I'm not terribly fussed about exactly what terms) in order to patch a port that requires it, and I'd be willing to add it to Pextlib or wherever it would be most appropriate. I'm fairly confident that my current implementation works as it should, but I haven't written a test suite for it yet, and I've been trying to think about how to make it more elegant and efficient.

[boeyms@…]

I take back my previous comment; in the case we have here, both strverscmp and the current rpm-vercomp function report 1.62001 as larger than 1.63 because they take the meaning of the dot (in this case) to be a integer separator rather than a decimal point. I don't believe that we could create a function that automatically detects this; MacPorts will only ever compare two version strings (the installed one and the latest one), and with that limited context there seems to be no way that one could tell whether, say, 2.11 versus 2.2 is supposed to be compared with the dot as a decimal point or as an integer separator.

I think that the only way to fix this would be to introduce another field into Portfiles (e.g. "version_comparison_method") to indicate which of these should be the case, and to add functionality for the decimal comparison case (which hopefully should not be too difficult).

[vinc17@…]

For Perl modules, the dot is always a decimal point, as said in the perlmodlib(1) man page: "This should be a floating point number with at least two digits after the decimal". So, the perl5 portgroup should be designed so that version comparisons work as expected for Perl modules, without having to add something to portfiles.

[eridius@…]

Nice idea, but there are a couple of ports that use the Perl5 group and don't follow this version format. For example net/smokeping, or perl/p5-astro-fits-header. But maybe we can work around these aberrant ports.

[vinc17@…]

The best solution would be to fix these ports. Otherwise the version comparison rule for the Perl5 group could be: if there is a single period, then use the comparison of floating-point numbers as described by the perlmodlib(1) man page; otherwise the usual MacPorts comparison should be used.

[jmpp@…]

Setting to "needs dev review" as no decision has been reached yet and I'll be closing the 1.4 milestone soon enough now.

-jmpp

[eridius@…]

Yeah I've been meaning to fix this but haven't had much time to work on MacPorts lately.

[jmpp@…]

Milestone Needs developer review deleted