Re^7: Modern Perl Programming Highs and Lows

In general, we'd much rather depend on a solid, tested module than poorly implement half of its functionality.

And there's the crux of the problem.

If you would only need to (poorly*) implement half of a module's functionality, then it means that by using it, your are also loading the other half of its functionality that you do not need. And that is deadweight.

It's like having: a people carrier for the seats; and a Ferrari for the speed; and a Rolls for the fridge; and a Citreon for the ride; and a Beemer for the Stereo; and a Volvo for the safety; and a Astra for the bike carrier; and a Polo for the iPod interface; and then loading them all onto a 40-ton car transporter and driving around in that to ensure you have everything you need!

The problem with many of these modules is that their basic functionality--the stuff you want--is relatively small, but the authors feel funny about putting a module on CPAN that only contains one or two small routines, so they add 3 or 4 other flavours of the basic routines that people "might find useful". And by the time you've loaded up a dozen dependancies, you've got 1/2 a meg of stuff you need, and 10 meg of stuff you never use.

If module authors used the Autoloader & Autosplit modules (as exemplified by modules like POSIX), so that their users could select what they need at compile time--or just stuck to providing the good bits without adding all the frills--then at least the problems of runtime bloat would recede.

(*)Why does it have to be poorly implemented? You have the good implementation as a crib. One possibility would be to produce a Moose::Utils module that extracts (and tailors) just the bits of your dependancies that you use, and ship that with Moose instead of the dependancies.

Moose gets just what it needs--which helps your start-up delays and runtime bloat problems.
Moose users get less dependancies and more performance.
Moose developers and users benefit from not suffering the vagries of random authors making random changes.
As dependancy modules change through upgrades and bug fixes, they can be integrated back into the Utils package in a controlled fashion--if needed.
Moose benefits from not suffering breaks, because of accidental reliance upon bugs that get fixed.
And it affords the opportunity to tune, prune and even improve those dependancies in ways that might even be useful fed back to the originating modules--without stalling your improvements waiting for author approval or tuits.

I realise that the idea of C&P reuse is an anathema most places, but re-use can be taken too far. The head/side/taillight requirements of most cars are pretty much standard, but the units are rarely re-used--even between models of the same manufacturer. The other criteria of the overall design--aerodynamics; aesthetics; etc.--dictate against such re-used despite the common requirements. The bulbs get re-used though!

Examine what is said, not who speaks -- Silence betokens consent -- Love the truth but pardon error.

"Science is about questioning the status quo. Questioning authority".

In the absence of evidence, opinion is indistinguishable from prejudice.

"Too many [] have been sedated by an oppressive environment of political correctness and risk aversion."

Comment on Re^7: Modern Perl Programming Highs and Lows

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Re^8: Modern Perl Programming Highs and Lows by perigrin (Sexton) on Apr 30, 2009 at 14:14 UTC
If you would only need to (poorly*) implement half of a module's functionality, then it means that by using it, your are also loading the other half of its functionality that you do not need. And that is deadweight. Actually Moose and Class::MOP between them use every single function Text::Exception exports. Ack through the test suite for yourself and see how pervasive it is. In general I would agree with the sentiment you have there, but Test::Exception is (ironically) the Exception that disproves this rule. As for 17 dependencies, I'm not sure where that number came from for Test::Exception, by my count it has 6 dependencies. One of the dependencies Sub::Uplevel is not a core Module, it in turn depends on Carp and Test::More. The rest of those dependencies are on dual life modules, sometimes that exist in a single dist (Test::Simple, Test::More, and Test::Builder are all explicitly named although last I checked they came in the same dist) and depend on versions that exist in 5.8.9's core but not in earlier core Modules. So if you are running perl 5.10.0 which has been out over a year, or 5.8.9 which has been out since December, you'll have those dependencies in core.	[reply]
Re^9: Modern Perl Programming Highs and Lows by perigrin (Sexton) on Apr 30, 2009 at 14:23 UTC
I now see why someone thinks Test::Exception has 17 dependencies. They trust someone else to do their resarch for them rather than actually going and looking at what it is they're asking. Yes if you assume that everyone is a Perl released over 6 years then yes Test::Exception will have 17 dependencies.	[reply]
Re^8: Modern Perl Programming Highs and Lows by chromatic (Archbishop) on Apr 30, 2009 at 18:06 UTC
As dependancy modules change through upgrades and bug fixes, they can be integrated back into the Utils package in a controlled fashion--if needed. I'm not sure the Moose developers want to be in the business of maintaining forks, especially given the risk of debugging (or merging) divergent behavior.	[reply]
Re^9: Modern Perl Programming Highs and Lows by BrowserUk (Patriarch) on May 01, 2009 at 02:38 UTC
I'm not sure the Moose developers want to be in the business of maintaining forks I think it only becomes a problem if you term it "forks"! Often as not, when you utilise subs from modules written by others, you end up writing your code around their interfaces. Adding glue code and coercions to take your data into and out of the forms required by the subs you utilise. And that has to either be done at each site you call those routines, or you wrap their sub in your own and do the coercions once there. Once you've wrapped their subs into your own wrappers, it's not a big step to lift their implementation into your wrapper to avoid or simplify the coercions required. From the sounds of things above, it looks like the Moose developers are already moving to replace some of their dependencies with XS code to improve their performance. Does that count as "forking"? Rolling up their dependencies into a support package, thereby isolating themselves from divergent development by myriad authors, could be a good first step on that road. As it would allow them to establish a dependency-free test-suite as a baseline for ensuring their XS conversions don't introduce bugs. It would also provide a pure-Perl fall-back position. One could even see the possibility of enlisting the help of the dependency authors in building and maintaining the individual parts of the Utils package. Enlisting their help and expertise in getting the "extractions" tailored to Moose requirements and maintaining them in line with developments in the dependency packages. That kind of cross-collaboration seems to be right in line with the aspirations of OSS. Still, I'm just floating ideas--with no expectation of anyone picking them up. Examine what is said, not who speaks -- Silence betokens consent -- Love the truth but pardon error. "Science is about questioning the status quo. Questioning authority". In the absence of evidence, opinion is indistinguishable from prejudice. "Too many [] have been sedated by an oppressive environment of political correctness and risk aversion."	[reply]