Thanks to the rather neat Algorithm::Dependency::Source::Invert, it turns out I can do a quick inverting of the dependency graph and then reuse all the same code to create the next Top 100 index.
As a result, I present way ahead of schedule the "CPANTS Volatile 100" index.
This index represents the distributions with the most downstream dependencies. Being higher on this index is not necessarily a good thing. It is not directly reflective of the popularity of any module, because if you already own one member of the index, it's easily to just make up a new module and add it as a dependency of the existing one (as in the chain of 4 IO-Compress modules you can see there).
The list more accurately represents the inherent volatility of the CPAN. That is, if the maintainer of a module is neglectful and issues a broken release, how big will the explosion be and how many other modules have you killed.
At the top of the list you can quite clearly see the set of modules with over 8,000 downstream dependent. This is the main section of the CPAN toolchain, or as Schwern and I like to call it, the OHMYGODIBROKECPAN zone.
Perhaps the most interesting thing about this zone is that there are some rather unexpected modules in there, particularly the Msql-Mysql-modules, HTTP-BrowserDetect, FreeWRL and Apache-LoggedAuthDBI ones...
CPANTS Volatile 100
8712 Scalar-List-Utils
8687 IO
8666 Data-Dumper
8650 Msql-Mysql-modules
8644 HTTP-BrowserDetect
8642 HTML-Widgets-Index
8627 Text-Tabs+Wrap
8624 FreeWRL
8621 Pod-Escapes
8619 Test-Harness
8619 Pod-Parser
8619 PathTools
8619 Test-Simple
8619 ExtUtils-Install
8619 Module-Build
8619 ExtUtils-MakeMaker
8619 Getopt-Long
8619 ExtUtils-Manifest
8619 File-Path
8619 podlators
8619 Pod-Simple
8619 ExtUtils-CBuilder
3471 Apache-LoggedAuthDBI
2954 MIME-Base64
2694 XSLoader
2597 URI
2533 File-Temp
2486 HTML-Tagset
2483 HTML-Parser
2373 IO-Compress-Base
2369 Compress-Raw-Zlib
2366 IO-Compress-Zlib
2363 Compress-Zlib
2351 libnet
2173 libwww-perl
1945 Sub-Uplevel
1940 Test-Exception
1681 version
1611 Class-Accessor
1555 Filter
1461 Storable
1324 Exporter
1279 Time-HiRes
1241 Test-Pod
1149 List-MoreUtils
1106 Class-Data-Inheritable
1030 FCGI
1018 Params-Util
960 Attribute-Handlers
952 CGI.pm
895 YAML
838 Encode
820 Params-Validate
820 Text-Balanced
818 UNIVERSAL-require
807 AppConfig
787 Template-Toolkit
783 Class-Inspector
756 Time-Local
737 Class-ISA
727 Module-Pluggable
726 IO-stringy
698 Sub-Install
696 Task-Weaken
685 Test-Tester
681 Data-OptList
678 Sub-Exporter
654 Devel-Symdump
651 Path-Class
634 Test-NoWarnings
618 MRO-Compat
598 XML-NamespaceSupport
587 XML-SAX
581 Pod-Coverage
573 Test-Pod-Coverage
525 Scope-Guard
509 IO-String
500 Tree-DAG_Node
498 Clone
495 Test-Deep
494 Array-Compare
491 Filter-Simple
485 Test-Warn
476 Sub-Name
471 TimeDate
462 UNIVERSAL-isa
460 NEXT
458 UNIVERSAL-can
456 Test-MockObject
451 Class-Singleton
441 Sub-Identify
440 DateTime-Locale
440 DateTime-TimeZone
438 DateTime
422 XML-Parser
414 HTTP-Body
408 Errno
405 Devel-GlobalDestruction
404 Class-MOP
401 Moose
Re:I don't trust those numbers
rjbs on 2009-02-11T14:50:28
My own results of this kind of analysis at http://dl.getdropbox.com/u/88746/cpan-prereqs.json.txt gave Msql-Mysql-modules a (very high) score of 21530, which backs up Alias's numbers. I can look at generating detailed dumps later today.
Re:I don't trust those numbers
rjbs on 2009-02-11T15:35:37
HTML-Widgets-Index requires DBD::mysql, which is part of Msql-Mysql-modules. CPANTS thinks that HTML-Widgets-Index is very well-used, because it thinks that it is the provider of the module "Test":
http://cpants.perl.org/dist/used_by/HTML-
Widgets-Indexhttp://cpants.perl.org/dist/provides/HTML-Widgets-Index
Re:I don't trust those numbers
Arador on 2009-02-11T16:05:39
Likewise, HTTP::BrowserDetect depends on HTML-Widgets-Index and FreeWRL 'provides' Config.Re:I don't trust those numbers
Arador on 2009-02-11T16:07:07
Oops, I meant of course HTML-Widgets-Index depends on HTTP::BrowserDetect.
Taking 'Tie-TinyURL' as an example, it requires 'Test', which is why it lists 'HTML-Widgets-Index' as being dependent. Except that Tie-TinyURL doesn't use 'Test' anywhere. I suspect this is a hangover for when it was ported to use Test::More, which it does use. This threw up a couple of ideas to help filter the results you're getting to something that is perhaps a little more relevent.
It would be helpful if authors noted the 'has_tests_in_t_dir' CPANTS indicator, but then CPANTS listing 'HTML-Widgets-Index' as the definitive source of 'Test' probably needs investigating. 02packages.details.txt.gz should be the definitive source, as used by the CPAN and CPANPLUS installers.
Re:Requires vs Recommends
Alias on 2009-02-11T23:57:01
> 1. Filter based on the 'requires' and/or 'recommends' entries in META.yml. If there is no META.yml, assume all pre-requisites are required.
I'm working on this one already, separating the weight and volatility graphs out into the different dependency layers (configure, build and runtime).
> It would be helpful if authors noted the 'has_tests_in_t_dir' CPANTS indicator, but then CPANTS listing 'HTML-Widgets-Index' as the definitive source of 'Test' probably needs investigating. 02packages.details.txt.gz should be the definitive source, as used by the CPAN and CPANPLUS installers.
This is probably the better fix for this. The CPANTS dependency data already includes a "0" distribution that represents the core, so it's not like the CPANTS data model doesn't support that. The problem looks to be that it's preferring a distribution ahead of the core for certain core-only namespaces.
