add support for Env arrays (from Gregor N. Purdy

<gregor@focusresearch.com>)

p4raw-id: //depot/perl@5405

1 files changed, 168 insertions, 12 deletions

diff --git a/lib/Env.pm b/lib/Env.pm
index b0afc3b2db..d1ee071cf8 100644
--- a/lib/Env.pm
+++ b/lib/Env.pm
@@ -2,57 +2,96 @@ package Env;
 
 =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-hash named %ENV.  For
+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 simple variables.
+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 $pack = shift;
-    my @vars = grep /^[A-Za-z_]\w*$/, (@_ ? @_ : 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, $_;
+	my ($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;
+	    }
+	}
     }
 }
 
@@ -74,4 +113,121 @@ sub STORE {
     }
 }
 
+######################################################################
+
+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;