package English;

our $VERSION = '1.00';

require Exporter;
@ISA = (Exporter);

=head1 NAME

English - use nice English (or awk) names for ugly punctuation variables

=head1 SYNOPSIS

    use English qw( -no_match_vars ) ;  # Avoids regex performance penalty
    use English;
    ...
    if ($ERRNO =~ /denied/) { ... }

=head1 DESCRIPTION

This module provides aliases for the built-in variables whose
names no one seems to like to read.  Variables with side-effects
which get triggered just by accessing them (like $0) will still 
be affected.

For those variables that have an B<awk> version, both long
and short English alternatives are provided.  For example, 
the C<$/> variable can be referred to either $RS or 
$INPUT_RECORD_SEPARATOR if you are using the English module.

See L<perlvar> for a complete list of these.

=head1 PERFORMANCE

This module can provoke sizeable inefficiencies for regular expressions,
due to unfortunate implementation details.  If performance matters in
your application and you don't need $PREMATCH, $MATCH, or $POSTMATCH,
try doing

   use English qw( -no_match_vars ) ;

.  B<It is especially important to do this in modules to avoid penalizing
all applications which use them.>

=cut

no warnings;

my $globbed_match ;

# Grandfather $NAME import
sub import {
    my $this = shift;
    my @list = grep { ! /^-no_match_vars$/ } @_ ;
    local $Exporter::ExportLevel = 1;
    if ( @_ == @list ) {
        *EXPORT = \@COMPLETE_EXPORT ;
        $globbed_match ||= (
	    eval q{
		*MATCH				= \$&	;
		*PREMATCH				= \$`	;
		*POSTMATCH				= \$'	;
		1 ;
	       }
	    || do {
		require Carp ;
		Carp::croak "Can't create English for match leftovers: $@" ;
	    }
	) ;
    }
    else {
        *EXPORT = \@MINIMAL_EXPORT ;
    }
    Exporter::import($this,grep {s/^\$/*/} @list);
}

@MINIMAL_EXPORT = qw(
	*ARG
	*LAST_PAREN_MATCH
	*INPUT_LINE_NUMBER
	*NR
	*INPUT_RECORD_SEPARATOR
	*RS
	*OUTPUT_AUTOFLUSH
	*OUTPUT_FIELD_SEPARATOR
	*OFS
	*OUTPUT_RECORD_SEPARATOR
	*ORS
	*LIST_SEPARATOR
	*SUBSCRIPT_SEPARATOR
	*SUBSEP
	*FORMAT_PAGE_NUMBER
	*FORMAT_LINES_PER_PAGE
	*FORMAT_LINES_LEFT
	*FORMAT_NAME
	*FORMAT_TOP_NAME
	*FORMAT_LINE_BREAK_CHARACTERS
	*FORMAT_FORMFEED
	*CHILD_ERROR
	*OS_ERROR
	*ERRNO
	*EXTENDED_OS_ERROR
	*EVAL_ERROR
	*PROCESS_ID
	*PID
	*REAL_USER_ID
	*UID
	*EFFECTIVE_USER_ID
	*EUID
	*REAL_GROUP_ID
	*GID
	*EFFECTIVE_GROUP_ID
	*EGID
	*PROGRAM_NAME
	*PERL_VERSION
	*ACCUMULATOR
	*DEBUGGING
	*SYSTEM_FD_MAX
	*INPLACE_EDIT
	*PERLDB
	*BASETIME
	*WARNING
	*EXECUTABLE_NAME
	*OSNAME
	*LAST_REGEXP_CODE_RESULT
	*EXCEPTIONS_BEING_CAUGHT
	*LAST_SUBMATCH_RESULT
	@LAST_MATCH_START
	@LAST_MATCH_END
);


@MATCH_EXPORT = qw(
	*MATCH
	*PREMATCH
	*POSTMATCH
);

@COMPLETE_EXPORT = ( @MINIMAL_EXPORT, @MATCH_EXPORT ) ;

# The ground of all being. @ARG is deprecated (5.005 makes @_ lexical)

	*ARG					= *_	;

# Matching.

	*LAST_PAREN_MATCH			= \$+	;
	*LAST_SUBMATCH_RESULT			= \$^N ;
	*LAST_MATCH_START			= \@- ;
	*LAST_MATCH_END				= \@+ ;

# Input.

	*INPUT_LINE_NUMBER			= \$.	;
	    *NR					= \$.	;
	*INPUT_RECORD_SEPARATOR			= \$/	;
	    *RS					= \$/	;

# Output.

	*OUTPUT_AUTOFLUSH			= \$|	;
	*OUTPUT_FIELD_SEPARATOR			= \$,	;
	    *OFS				= \$,	;
	*OUTPUT_RECORD_SEPARATOR		= \$\	;
	    *ORS				= \$\	;

# Interpolation "constants".

	*LIST_SEPARATOR				= \$"	;
	*SUBSCRIPT_SEPARATOR			= \$;	;
	    *SUBSEP				= \$;	;

# Formats

	*FORMAT_PAGE_NUMBER			= \$%	;
	*FORMAT_LINES_PER_PAGE			= \$=	;
	*FORMAT_LINES_LEFT			= \$-	;
	*FORMAT_NAME				= \$~	;
	*FORMAT_TOP_NAME			= \$^	;
	*FORMAT_LINE_BREAK_CHARACTERS		= \$:	;
	*FORMAT_FORMFEED			= \$^L	;

# Error status.

	*CHILD_ERROR				= \$?	;
	*OS_ERROR				= \$!	;
	    *ERRNO				= \$!	;
	*OS_ERROR				= \%!	;
	    *ERRNO				= \%!	;
	*EXTENDED_OS_ERROR			= \$^E	;
	*EVAL_ERROR				= \$@	;

# Process info.

	*PROCESS_ID				= \$$	;
	    *PID				= \$$	;
	*REAL_USER_ID				= \$<	;
	    *UID				= \$<	;
	*EFFECTIVE_USER_ID			= \$>	;
	    *EUID				= \$>	;
	*REAL_GROUP_ID				= \$(	;
	    *GID				= \$(	;
	*EFFECTIVE_GROUP_ID			= \$)	;
	    *EGID				= \$)	;
	*PROGRAM_NAME				= \$0	;

# Internals.

	*PERL_VERSION				= \$^V	;
	*ACCUMULATOR				= \$^A	;
	*COMPILING				= \$^C	;
	*DEBUGGING				= \$^D	;
	*SYSTEM_FD_MAX				= \$^F	;
	*INPLACE_EDIT				= \$^I	;
	*PERLDB					= \$^P	;
	*LAST_REGEXP_CODE_RESULT		= \$^R	;
	*EXCEPTIONS_BEING_CAUGHT		= \$^S	;
	*BASETIME				= \$^T	;
	*WARNING				= \$^W	;
	*EXECUTABLE_NAME			= \$^X	;
	*OSNAME					= \$^O	;

# Deprecated.

#	*ARRAY_BASE				= \$[	;
#	*OFMT					= \$#	;
#	*MULTILINE_MATCHING			= \$*	;
#	*OLD_PERL_VERSION			= \$]	;

1;