On Jan 27, 2009, at 5:47 PM, Michael G Schwern wrote:
A good solution is to have a single policy of what to do
(execute/ask/disallow) and the meta-file contain defaults if their
executables
are not run. This is analogous to how prompt() works.
As I said in my previous email, if I'm installing your code, I'm going
to be running it, anyway. So why can't the build script be written in
Perl?
It is also critical to realize that custom code parts would be
considered
*exceptional* rather than normal and the drive would be to eliminate
them.
See below.
This is true now for Module::Build. The vast majority of Build scripts
look something like this:
use Module::Build;
my $build = Module::Build->new(
module_name => 'FSA::Rules',
license => 'perl',
create_makefile_pl => 'passthrough',
create_readme => 1,
requires => { perl => 5.006_002 },
configure_requires => { 'Module::Build' => '0.2701' },
build_requires => {
'Module::Build' => '0.2701',
'Test::More' => '0.17',
},
recommends => {
'GraphViz' => '2.00',
'Text::Wrap' => 0,
'Storable' => '2.05',
'B::Deparse' => '0.61',
'Test::Pod' => '1.20',
},
);
$build->create_build_script;
See? All metadata. So what does an alternate format buy you? As a Perl
author, I'm more comfortable editing my build configuration in Perl
than in YAML or JSON or just about anything else.
I wouldn't want it in SQL, though. Ick. Wrong hammer for this pylon. ;-)
The advantage of the meta-file is it can absorb more and more use
cases things
need less and less custom code. This is critical: it improves over
time!
Custom code is already the exception. What would simplify the custom
code problem, IMHO, is adding support for plugins to Module::Build.
name: Foo-Bar
version: from('lib/Foo/Bar.pm')
abstract: from('lib/Foo/Bar.pm')
authors:
- Michael G Schwern <schw...@pobox.com>
license: perl
requires:
everywhere:
File::Spec: 0.8
perl: 5.6.1
os_is('Win32'):
Win32::Thing: 1.23
sub { -x "/usr/bin/mysql" }:
DBD::mysql: 0
So if we had a plugin system in Module::Build, we'd be able to do
something like this:
use Module::Build plugins => [qw(OS FS)];
Module::Build->new(
module_name => 'Foo::Bar',
license => 'perl',
requires => [
File::Spec => '0.8',
perl => '5.6.1',
(os_is('Win32') ? (Win32::Thing => '1.23') : ()),
(has_bin('mysql') ? (DBD::mysql => 0) : ()),
],
);
Hell, we could even have simple functions that return values, like:
requires => [
File::Spec => '0.8',
perl => '5.6.1',
os_requires('Win32', Win32::Thing => '1.23'),
bin_requires('mysql', DBD::mysql => 0),
],
Much easier to write than YAML.
However, we can't just use a Perl program because it's Perl and can do
anything at all. This blows the whole point of a meta-file out of
the water,
that it can be trusted. That it can be read without executing
arbitrary code.
Isn't that what META.yml is for already?
Best,
David
