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#! perl
########################################################################
# Copyright ( C ) 2006 ERG Limited, All rights reserved
#
# Module name   : jats.sh
# Module type   : Makefile system
# Compiler(s)   : n/a
# Environment(s): jats
#
# Description   : Provide some misc environment functions
#                 Note this is not a "package" as we will be importing
#                 variables directly into the users space.
#
# Usage:
#
# Version   Who      Date        Description
#
#......................................................................#

require 5.6.1;

use strict;
use warnings;
use JatsError;

#-------------------------------------------------------------------------------
# Function        : EnvImport
#
# Description     : Import an environment variable into the current user space
#                   The user should have pre-declared the usage of the variable
#                   with an "our". For this reason this package is not a
#                   'package'. Rather it is simply imported.
#
# Inputs          : Name of the environment varibale to import
#
# Returns         : 1
#                   If the variable is not present then an error message is
#                   generated and the program will be termianted. The assumption
#                   is tha the variable MUST be present.
#
sub EnvImport
{
    my( $EnvVar ) = @_;

    no strict 'refs';
    unless ( defined( $$EnvVar ) ) {
        $$EnvVar = $ENV{ $EnvVar };
    }
    use strict;

    Error( "Environment Variable '$EnvVar' not defined." )
        unless( defined $$EnvVar );

    return 1;
}

#-------------------------------------------------------------------------------
# Function        : EnvImportOptional
#
# Description     : Import an environment variable into the current user space
#                   The user should have pre-declared the usage of the variable
#                   with an "our". For this reason this package is not a
#                   'package'. Rather it is simply imported.
#
#                   If no default value is provided and the variable does not
#                   exist in the environment, then result will be undefined
#
# Inputs          : Name of the environment varibale to import
#                   Default value
#
# Returns         : 1
#
sub EnvImportOptional
{
    my( $EnvVar, $DefaultValue ) = @_;

    my $value = $ENV{ $EnvVar } || $DefaultValue;

    no strict 'refs';
    unless ( defined( $$EnvVar ) ) {
        $$EnvVar = $value;
    }
    use strict;
    
    return 1;
}

1;