I need to write an XS module for Perl. It is my understanding that h2xs is pretty much deprecated today, what is the preferred method for starting an XS module today? I looked at Module::Starter, but it only handles pure Perl modules.
No, h2xs is not deprecated. Module::Starter is certainly more convenient if you create many pure Perl modules, but there's no reason to avoid h2xs. I would recommend reading all the way through its doc before using it, though, so that you know what all you might want it to do or not do.
Personally I just use Module::Starter and add the .xs file myself. It depends on what your aim is: if you're making a one-on-one mapping to a C api then h2xs can do a lot of boilerplate for you, but if you're making a completely new interface, or when you're only doing things with perl itself (and not some external library) it doesn't add much but trouble IMHO.
Personally, whenever I start making a new module I just do it by cping and editing files from another module of mine that's similar to it, and editing as appropriate. Of course, nothing in that approach says it has to be one of mine. There's plenty of code on CPAN you can take copies of and be inspired by...
You should also look at using Inline::C
Related
In python there is ctypes, which allow me to load and call libraries.
Is there an equivalent in perl?
The reason I want to do this, is that I am working on a closed platform where I cannot install any modules, but there is an abundance of shared libraries.
Such equivalent must of course be native for perl...
Yes. In Perl, this is called XS.
If you want to call functions in shared libs I suggest that you take a look at Inline::C, https://metacpan.org/pod/Inline::C. There is a cookbook, https://metacpan.org/pod/Inline::C-Cookbook, for getting started.
There also were some attempts to use libffic from Perl, but I don't know how far these went.
I am creating a bigger application in Perl, and I am wondering whether something like class autoloading similar to php’s can be done in Perl?
I checked catching exceptions and $SIG{__DIE__} redefining etc., but this doesn't seem to be solution because it will be stopped on first “cannot find method new via package”, and then to load every module I should again call the whole program.
One solution could be to maybe scan all files in my lib and give it to #INC at runtime, but I don’t know whether this is good solution — probably not.
Do anybody have a suggestion?
Well, you probably want to read up on the following:
AUTOLOAD and AutoLoader
autouse
Class::AutoUse
later
etc.
None of those are quite the same as PHP's approach though.
However, it really is best practice to list all "normal" dependencies. This makes it easier to build installers / deploy to CPAN etc. There are a bunch of other modules that deal with loading plugins, where you really don't know what to load until runtime.
Is there some difficulty with figuring out your dependencies, or do you just want to avoid a bunch of "use" statements at the top of each file?
I'm writing a programmer's text editor (yes another one) in Perl called Kephra, which is also a CPAN module of course and bundled with Module::Install. Recently I saw that Module::Build has gone into core, so if I switch I could reduce dependencies. Is there any other reason to switch?
We use Module::Build in our group.
The main reason is Easy Extensibility.
Module::Build allows you to do more with your build process in pure Perl through subclassing. If you want to do more using Module::Install, you have to have knowledge of how Makefiles work, AFAIK. Since you presumably already know Perl, this can be an advantage.
As you said, using Module::Build removes the dependency on an external make program, which can be viewed as a good thing.
However, the main cons that I can think of are:
Although Module::Build has hit core, not everyone will be using an up-to-date version of Perl. For users with older versions of the core, you will be creating a new dependency.
Lots of veterans (not necessarily Perl people) are used to the perl Makemaker.PL; make; make install paradigm, and can be thrown off by having Build.PL instead. Hopefully this isn't a big deal.
Module::Build has occasionally broken our builds when its functionality has changed because the documentation didn't cover an edge case which we were using. The edge case was then changed and documented, but we had to re-code our subclass to get our build to work again (this happened for us at the recent upgrade from 0.2808 to 0.3).
All that said, though, I still recommend Module::Build simply for the extensibility. If that's not an issue for you, you may be better off sticking with Module::Install.
The cud as already been chewed a bit on this before in "Which framework should I use to write modules?"
After spitting out the cud I decided to go with Module::Build but clearly different answers are possible! (though I've been happy with M::B so far).
Well, Module::Build is a pretty good module, it's supposed to be a drop in replacement for ExtUtils::MakeMaker, that is, replace the Makefile.PL by a Build.PL, which generate a Build instead of a Makefile. It was also meant as "simple things should stay simple, hard things should be possible".
Module::Install takes a different approach and generates a Makefile.
Also, don't forget that not everyone runs the latest version of everything :-)
I don't remember any comparison of those modules, but I think you could find a few things from Module::Build and Module::Install respective cpanratings pages.
Are there any libraries out there that do this? Playing around with Common Lisp it seems like this would be one of the most useful things to lower barrier of entry for newcomers. ASDF seems mostly designed for deployment, not for rapid prototyping and development. Following threads on comp.lang.lisp it seems like people agree that CL's package system is powerful, but lacks the ease of something like Python's dead simple module system. It is FAIL in the sense that it's designed for power not usability.
Glad to know if I'm wrong. If I'm right, I'm stunned that noone has tried to build a Python module-like system on top of ASDF.
Zach Beane wrote how he nowadays starts new Common Lisp projects by using Quicklisp and Quickproject. This might be along the lines you want.
Not sure if it's ready for prime time or whether it fits your requirements at all, but here's a link to XCVB.
I don't know. I mostly use ASDF for my in-development compilation needs. Once you notice that you'd benefiot from more than one source file, open <projectname>.asd, slap in a basic ASDF system definition template and start slapping filenames in. As and when you notice a cross-file dependency, update the dependency list.
But, then, I use the exact same method dealing with Makefiles (yes, I know there are automatic dependency checkers that can do it for you, but since I mostly code on my own, it's easier to just amend the Makefile/ASDF definition as I go).
In SBCL, there's a hook on REQUIRE that checks for ASDF systems, so you end up with something that is about as convenient as Python's import, but somehow I suspect that is not what you meant.
This may not be the answer you want, but clearly you have some idea of what you want in a module system. Have you considered creating one yourself? That is, taking your limited domain, your limited requirements, your environment and simply pounding out whatever abstractions will quickly make your life easier?
That's one of the key benefits of Lisp I'm sure you know, is that these simple abstractions and little tools are typically very easy to craft in Lisp.
I'm not suggesting solving everyone who has a problem with the package system or ASDF, I'm simply suggesting solving your own problem as you understand it, which is likely simpler and smaller than some more powerful larger scope.
There is Mudballs now, too.
If you're looking for a piece of software to add this functionality to then it's a good bet.
If you want a command line tool that just uses bash to generate new common lisp project directory and file layouts, you may find one that I created for myself useful: lispproject. If it doesn't match your needs, go ahead and fork it or the repo it gets it templates from to suit your needs: lisp-project-template. Look at the sh file in lispproject repo to see how the templates are used. Also, please note that you may need to adjust the calls to sed to fit your platform as I am using this on macOS. Alternative sed calls are in the main script but just commented out if you need them.
it's designed for power not usability
that's how most Lisp gurus like it.
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What's the best framework for writing modules -- ExtUtils::MakeMaker (h2xs) or Module::Build?
NOTE This advice is out of date. Module::Build has been removed from the Perl core but lives on as a CPAN module. The pros and cons still stand, and my opinions about MakeMaker still stand.
As the former maintainer of ExtUtils::MakeMaker, I like to recommend Module::Build because MakeMaker is a horror show. Module::Build is so much better put together. But those aren't your concerns and I'll present my "least hassle for you" answer.
Executive Summary:
Because Module::Build support is not 100% in place through all of Perl, start with MakeMaker. If you want to do any customization at all, switch to Module::Build. Since their basic layout, options and interface are almost identical this will be painless. As seductive as it looks, avoid Module::Install.
Fortunately, Module::Build can emulate MakeMaker which helps some, but doesn't help if you're going to do any customization. See Module::Build::Compat.
For CPAN releases using Module::Build is fine. There's enough Module::Build stuff on CPAN now that everyone's dealt with getting it bootstrapped already.
Finally, the new configure_requires option lets CPAN shells know to install Module::Build before they can start building the module. Unfortunately only the latest CPAN shells know about configure_requires.
Oh, whatever you do don't use h2xs (unless you're writing XS code... and even then think about it).
MakeMaker Pros:
Comes with Perl and used by the Perl core (therefore it is actively
maintained and will remain so forever)
Everything knows what to do with a Makefile.PL.
Most module authoring documentation will cover MakeMaker.
Uses make (those who know make can debug and patch the build
process)
MakeMaker Cons:
Requires make (think Windows)
Difficult to customize
Even harder to customize and make cross platform
Difficult to debug when something goes wrong (unless you understand make)
Module::Build Pros:
Easier to customize/subclass
Pure Perl
Easier to debug (it's Perl)
Can emulate MakeMaker in several ways
The CPAN shell will install Module::Build for you
Module::Build Cons:
The Module::Build maintainers (and indeed all of the Perl Toolchain Gang) hate it
Older versions of CPAN clients (including CPANPLUS) don't know anything about Module::Build.
Module::Install Pros:
Slick interface
Bundles itself, you have a known version
Everything knows how to deal with a Makefile.PL
Module::Install Cons:
Requires make
Always uses bundled version, vulnerable to external breakage
Difficult to customize outside its interface
Mucks with the guts of MakeMaker so a new MakeMaker release will eventually break it.
Does not know how to generate a META file using the v2 meta-spec
(increasingly a problem with newer tools)
There are two questions here.
First, never use h2xs. It's old outdated nastiness, though I suppose if you're actually trying to turn a header file into XS code, it might be useful (never done that myself).
2011 update: I strongly recommend taking a look at Dist::Zilla, especially if you think you'll be maintaining more than one module.
For creating a new module, use Module::Starter. It works great, and has some nice plugins for customizing the output.
Second, you're asking what build system you should use. The three contenders are ExtUtils::MakeMaker (EUMM), Module::Build (MB), and Module::Install (MI).
EUMM is a horrid nasty piece of work, but it works, and if you're not customizing your build process at all, works just fine.
MB is the new kid, and it has its detractors. It's big plus is that if you want to heavily customize your install and build process, it's quite possible to do this sanely (and in a cross-platform manner) using MB. It's really not possible using EUMM.
Finally, MI is basically a declarative wrapper on top of EUMM. It also packages itself along with your distro, in an attempt to work around problems with users trying to install modules with old toolchain modules. The downside of the "package self" trick is that if there's a bug in MI itself, you have to re-release all your modules just to fix it.
As far as customization goes, there are some plugins for MI, but if you want to go beyond them you'll be back at the problem of dealing with Makefiles and build tools across a dozen+ platforms, so it really isn't going to help you too much in that realm.
I just uploaded Distribution::Cooker to CPAN. It's what I use to make new distributions. The nice thing about it is that your distributions can be whatever you like: you're just cooking some templates. I don't care if anyone uses it. For me it's simple, low tech, and doesn't cause extra problems.
You might start with something like Module::Starter to make your starter templates then add your own boilerplate and favorite way of doing things. You choose not only whatever you want in each file, but which files show up in the distro. As you figure out how you like to do things, you simply update your own templates.
As for Makemaker and Module::Build, the future is Module::Build. It's only us old guys using Makemaker anymore. :) There are ways to use both (or pretend to use both) at the same time. Look at the Module::Build, Module::Build::Compat, and Module::Install docs. Module::Build was kicked out of Perl's Standard Library and it's future is uncertain. It's back to Makemaker as a build system.
Although this is a bit of a cop-out answer, try using each just to get a little experience with each.
You also might want to look at Dist-Zilla which is a new author-only tool to create distributions. Because it just helps build the distribution, it doesn't ship with your code or do any installation, it can do a lot of powerful stuff.
The only trouble with compatibility regarding Module::Build is when a user tries to install modules without updating their CPAN client (CPAN.pm or CPANPLUS.pm) If they are installing your module from the CPAN, they can just as easily upgrade their client from the same mirror.
If you don't want to do anything complicated in your build process, sure: use EUMM. But if you have a build problem on a different target platform, you might end up in the Makefile, which is different on every variation of make.
Module::Build gives you lots of features (anything you can think of if you extend it) and is all perl so you never end up debugging a makefile. Module::Install gives you features, but you have to bundle it and everything ends up running through 'make' in the end.
I also recommend Module::Build and Module::Starter (with the TT2 plugin).
Module::Build is better by any means, but it is less widely supported than ExtUtils::MakeMaker (more specifically, older versions of Perl don't support it out of the box). It depends on your needs.
Personally, I recommend Module::Install, as do a lot of folks I know - the likes of the Catalyst and Moose folks also use it.
Here's a little clarification of the direction I hoped the responses would take:
pros/cons of various of frameworks
compatibility/install base of frameworks
suitability for internal (local) vs. external (CPAN) releases
not bare "use X" answers
Dave's answer has some good pro/con info. Leon's answer alludes to compatibility but isn't explicit. As brian d foy mentioned, only the old hats use EUMM, but I'm not convinced that MB is a good framework for things destined for CPAN due to it not being part of the core until 5.9.
There are pros and cons to both. These days I use and recommend Module::Build and Module::Starter.
EU::MM still seems to be the most widely supported and popular one, but Module::Build is catching up. Also, check out Module::Starter for a module that will help you get started.