cpanfile-faq(3pm)					User Contributed Perl Documentation					 cpanfile-faq(3pm)

NAME

       cpanfile-faq - cpanfile FAQ

QUESTIONS

   Does cpanfile replace Makefile.PL or Build.PL?
       No, it doesn't. "cpanfile" is a simpler way to declare CPAN dependencies, mainly to your application rather than CPAN distributions.

       In fact, most CPAN distributions do not need to switch to "cpanfile" unless they absolutely want to take advantage of some of the features
       (see below). This is considered a new extension for applications and installers.

   Why do we need yet another format?
       Here are some of the reasons that motivates the new cpanfile format.

       Not everything is a CPAN distribution
	   First of all, it is annoying to write Makefile.PL when what you develop is not a CPAN distirbution.

	   It gets more painful when you develop a web application that you want to deploy on a different environment using version control system
	   (such as cloud infrastructure), because it requires you to often commit the META file or "inc/" directory (or even worse, botu) to a
	   repository when your build script uses non-core modules such as Module::Install or File::Copy::Recursive.

	   Many web application frameworks generate a boiler-plate "Makefile.PL" for dependency declaration and to let you install dependencies
	   with "cpanm --installdeps .", but that doesn't always mean they are meant to be installed. Things can be often much simpler if you run
	   the application from the checkout directory.

	   With cpanfile, dependencies can be installed either globally or locally using supported tools such as cpanm or carton. Because
	   "cpanfile" lists all the dependencies of your entire application and will be updated over time, it makes perfect sense to commit the
	   file to a version control system, and push the file for a deployment.

       More control for the dependencies analysis
	   One of the limitation when I tried to implement a self-contained local::lib library path feature for cpanminus was that the
	   configuration phase runs the build file as a separate perl process, i.e. "perl Makefile.PL".

	   This makes it so hard for the script to not accidentally load any modules installed in the local "site_perl" directory when determining
	   the dynamic dependencies. With the recent evolution of CPAN installer ecosystem such as local::lib support, it makes things much easier
	   if installers figure out whether dependencies are installed, instead of by build tools such as Module::Install.

       Familiar DSL syntax
	   This is a new file type, but the format and syntax isn't entirely new. The metadata it can declare is exactly a subset of "Prereqs" in
	   CPAN Meta Spec, with some conditionals such as "platform" and "perl".

	   The syntax borrows a lot from Module::Install. Module::Install is a great way to easily declare module metadata such as name, author
	   and dependencies. cpanfile format is simply to extract the dependencies into a separate file, which means most of the developers are
	   familiar with the syntax.

       Complete CPAN Meta Spec v2 support
	   "cpanfile" basically allows you to declare CPAN::Meta::Spec prerequisite specification using an easy Perl DSL syntax. This makes it
	   easy to declare per-phase dependencies and newer version 2 features such as conflicts and version ranges.

   How can I start using "cpanfile"?
       First of all, most distributions on CPAN are not required to update to this format.

       If your application currently uses "Makefile.PL" etc. for dependency declaration because of the current toolchain implementation (e.g.
       "cpanm --installdeps ."), you can upgrade to "cpanfile" while keeping the build file based installation working for the backward
       compatibility.

       TBD: Support in other tools such as MakeMaker

perl v5.14.2							    2012-04-04							 cpanfile-faq(3pm)