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lib/ExtUtils/InferConfig.pm  view on Meta::CPAN

use IPC::Cmd qw//;

use vars qw/$VERSION/;
BEGIN {
    $VERSION = '1.04';
}

#use constant ISWIN32 => ($^O =~ /win32/i ? 1 : 0);

=head1 NAME

ExtUtils::InferConfig - Infer Perl Configuration for non-running interpreters

=head1 SYNOPSIS

  use ExtUtils::InferConfig;
  my $eic = ExtUtils::InferConfig->new(
    perl => '/path/to/a/perl'
  );
  
  # Get that interpreters %Config as hash ref
  my $Config = $eic->get_config;
  
  # Get that interpreters @INC as array ref
  my $INC = $eic->get_inc;

=head1 DESCRIPTION

This module can determine the configuration and C<@INC> of a perl
interpreter given its path and that it is runnable by the current
user.

It runs the interpreter with a one-liner and grabs the C<%Config>
hash via STDOUT capturing. Getting the module load paths, C<@INC>,
works the same way for C<@INC> entries that are plain paths.

=head1 METHODS

=head2 new

Requires one named parameter: C<perl>, the path to the perl
interpreter to query for information.

Optional parameter: C<debug =E<gt> 1> enables the debugging mode.

=cut

sub new {
    my $class = shift;
    $class = ref($class) || $class;

    my %args = @_;


    my $self = {
        perl => undef,
        config => undef,
        inc => undef,
        ($args{debug} ? (debug => 1) : ()),
    };
    bless $self => $class;

    # get interpreter, check that we have access
    my $perl = $args{perl} || $^X;
    $perl = $self->_perl_to_file($perl);

    if (not defined $perl) {
        croak(
            "Invalid perl interpreter specified. "
            ."It was either not found or it is not executable."
        );
    }

    warn "Using perl '$perl'" if $self->{debug};

    $self->{perl} = $perl;

    return $self;
}

sub _perl_to_file {
    # see perldoc perlvar about this. Look for $^X
    my $self = shift;
    my $perl = shift;

    return() if not defined $perl;
    return $perl if -f $perl and -x _;

    # Build up a set of file names (not command names).
    if ($^O ne 'VMS') {
      $perl .= $Config{_exe}
        unless $perl =~ m/\Q$Config{_exe}$/i;
    }

    return $perl if -f $perl and -x _;
    return();
}


=head2 get_config

Returns a copy of the C<%Config::Config> hash of the
intepreter which was specified as a parameter to the
constructor.

The first time this method (or the get_inc method below)
is called, the perl binary is run. For subsequent calls
of this method, the information is cached.

=cut

sub get_config {
    my $self = shift;
    return $self->{config} if defined $self->{config};

    $self->{config} = $self->_infer_config($self->{perl});

    return $self->{config};
}

sub _infer_config {