package Env;
+our $VERSION = '1.00';
+
=head1 NAME
-Env - perl module that imports environment variables
+Env - perl module that imports environment variables as scalars or arrays
=head1 SYNOPSIS
use Env;
use Env qw(PATH HOME TERM);
+ use Env qw($SHELL @LD_LIBRARY_PATH);
=head1 DESCRIPTION
-Perl maintains environment variables in a pseudo-associative-array
-named %ENV. For when this access method is inconvenient, the Perl
-module C<Env> allows environment variables to be treated as simple
-variables.
+Perl maintains environment variables in a special hash named C<%ENV>. For
+when this access method is inconvenient, the Perl module C<Env> allows
+environment variables to be treated as scalar or array variables.
-The Env::import() function ties environment variables with suitable
+The C<Env::import()> function ties environment variables with suitable
names to global Perl variables with the same names. By default it
-does so with all existing environment variables (C<keys %ENV>). If
-the import function receives arguments, it takes them to be a list of
-environment variables to tie; it's okay if they don't yet exist.
+ties all existing environment variables (C<keys %ENV>) to scalars. If
+the C<import> function receives arguments, it takes them to be a list of
+variables to tie; it's okay if they don't yet exist. The scalar type
+prefix '$' is inferred for any element of this list not prefixed by '$'
+or '@'. Arrays are implemented in terms of C<split> and C<join>, using
+C<$Config::Config{path_sep}> as the delimiter.
After an environment variable is tied, merely use it like a normal variable.
You may access its value
@path = split(/:/, $PATH);
+ print join("\n", @LD_LIBRARY_PATH), "\n";
or modify it
$PATH .= ":.";
+ push @LD_LIBRARY_PATH, $dir;
+
+however you'd like. Bear in mind, however, that each access to a tied array
+variable requires splitting the environment variable's string anew.
+
+The code:
+
+ use Env qw(@PATH);
+ push @PATH, '.';
+
+is equivalent to:
+
+ use Env qw(PATH);
+ $PATH .= ":.";
+
+except that if C<$ENV{PATH}> started out empty, the second approach leaves
+it with the (odd) value "C<:.>", but the first approach leaves it with "C<.>".
-however you'd like.
To remove a tied environment variable from
the environment, assign it the undefined value
undef $PATH;
+ undef @LD_LIBRARY_PATH;
+
+=head1 LIMITATIONS
+
+On VMS systems, arrays tied to environment variables are read-only. Attempting
+to change anything will cause a warning.
=head1 AUTHOR
Chip Salzenberg E<lt>F<chip@fin.uucp>E<gt>
+and
+Gregor N. Purdy E<lt>F<gregor@focusresearch.com>E<gt>
=cut
sub import {
my ($callpack) = caller(0);
my $pack = shift;
- my @vars = @_ ? @_ : keys(%ENV);
+ my @vars = grep /^[\$\@]?[A-Za-z_]\w*$/, (@_ ? @_ : keys(%ENV));
return unless @vars;
- eval "package $callpack; use vars qw("
- . join(' ', map { '$'.$_ } @vars) . ")";
+ @vars = map { m/^[\$\@]/ ? $_ : '$'.$_ } @vars;
+
+ eval "package $callpack; use vars qw(" . join(' ', @vars) . ")";
die $@ if $@;
foreach (@vars) {
- tie ${"${callpack}::$_"}, Env, $_ if /^[A-Za-z_]\w*$/;
+ my ($type, $name) = m/^([\$\@])(.*)$/;
+ if ($type eq '$') {
+ tie ${"${callpack}::$name"}, Env, $name;
+ } else {
+ if ($^O eq 'VMS') {
+ tie @{"${callpack}::$name"}, Env::Array::VMS, $name;
+ } else {
+ tie @{"${callpack}::$name"}, Env::Array, $name;
+ }
+ }
}
}
}
}
+######################################################################
+
+package Env::Array;
+
+use Config;
+use Tie::Array;
+
+@ISA = qw(Tie::Array);
+
+my $sep = $Config::Config{path_sep};
+
+sub TIEARRAY {
+ bless \($_[1]);
+}
+
+sub FETCHSIZE {
+ my ($self) = @_;
+ my @temp = split($sep, $ENV{$$self});
+ return scalar(@temp);
+}
+
+sub STORESIZE {
+ my ($self, $size) = @_;
+ my @temp = split($sep, $ENV{$$self});
+ $#temp = $size - 1;
+ $ENV{$$self} = join($sep, @temp);
+}
+
+sub CLEAR {
+ my ($self) = @_;
+ $ENV{$$self} = '';
+}
+
+sub FETCH {
+ my ($self, $index) = @_;
+ return (split($sep, $ENV{$$self}))[$index];
+}
+
+sub STORE {
+ my ($self, $index, $value) = @_;
+ my @temp = split($sep, $ENV{$$self});
+ $temp[$index] = $value;
+ $ENV{$$self} = join($sep, @temp);
+ return $value;
+}
+
+sub PUSH {
+ my $self = shift;
+ my @temp = split($sep, $ENV{$$self});
+ push @temp, @_;
+ $ENV{$$self} = join($sep, @temp);
+ return scalar(@temp);
+}
+
+sub POP {
+ my ($self) = @_;
+ my @temp = split($sep, $ENV{$$self});
+ my $result = pop @temp;
+ $ENV{$$self} = join($sep, @temp);
+ return $result;
+}
+
+sub UNSHIFT {
+ my $self = shift;
+ my @temp = split($sep, $ENV{$$self});
+ my $result = unshift @temp, @_;
+ $ENV{$$self} = join($sep, @temp);
+ return $result;
+}
+
+sub SHIFT {
+ my ($self) = @_;
+ my @temp = split($sep, $ENV{$$self});
+ my $result = shift @temp;
+ $ENV{$$self} = join($sep, @temp);
+ return $result;
+}
+
+sub SPLICE {
+ my $self = shift;
+ my $offset = shift;
+ my $length = shift;
+ my @temp = split($sep, $ENV{$$self});
+ if (wantarray) {
+ my @result = splice @temp, $self, $offset, $length, @_;
+ $ENV{$$self} = join($sep, @temp);
+ return @result;
+ } else {
+ my $result = scalar splice @temp, $offset, $length, @_;
+ $ENV{$$self} = join($sep, @temp);
+ return $result;
+ }
+}
+
+######################################################################
+
+package Env::Array::VMS;
+use Tie::Array;
+
+@ISA = qw(Tie::Array);
+
+sub TIEARRAY {
+ bless \($_[1]);
+}
+
+sub FETCHSIZE {
+ my ($self) = @_;
+ my $i = 0;
+ while ($i < 127 and defined $ENV{$$self . ';' . $i}) { $i++; };
+ return $i;
+}
+
+sub FETCH {
+ my ($self, $index) = @_;
+ return $ENV{$$self . ';' . $index};
+}
+
1;
https://perl5.git.perl.org / perl5.git / blobdiff