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########################################################################
# Copyright ( C ) 2006 ERG Limited, All rights reserved
#
# Module name   : JatsEnv.pm
# Module type   : Perl Module
# Compiler(s)   : Perl
# Environment(s): JATS
#
# Description   : Provide some misc environment functions
#
# Usage         : EnvImport (VarName);
#                 EnvImportOptional (VarName [, DefaultValue]);
#
#
#......................................................................#

require 5.006_001;

use strict;
use warnings;

package JatsEnv;
use JatsError;


our (@ISA, @EXPORT, @EXPORT_OK, %EXPORT_TAGS, $VERSION);
use Exporter;

$VERSION = 1.00;
@ISA = qw(Exporter);

# Symbols to autoexport (:DEFAULT tag)
@EXPORT = qw(
                EnvImport
                EnvImportOptional
            );

#-------------------------------------------------------------------------------
# Function        : EnvImport
#
# Description     : Import an environment variable into the global name space
#                   The user should have pre-declared the usage of the variable
#                   with an "our".
#
# Inputs          : Name of the environment variable to import
#
# Returns         : 1
#                   If the variable is not present then an error message is
#                   generated and the program will be terminated. The assumption
#                   is that the variable MUST be present.
#
sub EnvImport
{
    my( $EnvVar ) = @_;

    EnvImportOptional ( $EnvVar, undef );

    Error( "Environment Variable '$EnvVar' not defined." )
        unless( defined ${$main::{$EnvVar}} );

    return 1;
}

#-------------------------------------------------------------------------------
# Function        : EnvImportOptional
#
# Description     : Import an environment variable into the global name space
#                   The user should have pre-declared the usage of the variable
#                   with an "our".
#
#                   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 variable to import
#                   Default value
#
# Returns         : 1
#
sub EnvImportOptional
{
    my( $EnvVar, $DefaultValue ) = @_;

    unless ( defined( ${$main::{$EnvVar}} ) ) {

        my $value = $ENV{ $EnvVar };
        $value = $DefaultValue unless ( defined $value );
        ${$main::{$EnvVar}} = $value;
    }
    return 1;
}

1;