latest switch/say/~~

Message-Id: <20051217204431.GB28940@rpc142.cs.man.ac.uk>

p4raw-id: //depot/perl@26400

4 files changed, 134 insertions, 197 deletions

diff --git a/lib/feature.pm b/lib/feature.pm
new file mode 100644
index 0000000000..e0981d08a9
--- /dev/null
+++ b/lib/feature.pm
@@ -0,0 +1,116 @@
+package feature;
+
+our $VERSION = '1.00';
+$feature::hint_bits = 0x04020000; # HINT_LOCALIZE_HH | HINT_HH_FOR_EVAL
+
+# (feature name) => (internal name, used in %^H)
+my %feature = (
+    switch => 'switch',
+    "~~"   => "~~",
+    say    => "say",
+);
+
+
+# Here are some notes that probably shouldn't be in the public
+# documentation, but which it's useful to have somewhere.
+#
+# One side-effect of the change is that C<prototype("CORE::continue")>
+# no longer throws the error C<Can't find an opnumber for "continue">.
+# One of the tests in t/op/cproto.t had to be changed to accommodate
+# this, but it really shouldn't affect real-world code.
+#
+# TODO:
+# - sort out the smartmatch semantics
+# - think about versioned features (use switch => 2)
+#
+# -- Robin 2005-12
+
+=head1 NAME
+
+feature - Perl pragma to enable new syntactic features
+
+=head1 SYNOPSIS
+
+    use feature 'switch';
+    given ($foo) {
+	when (1)	  { print "\$foo == 1\n" }
+	when ([2,3])	  { print "\$foo == 2 || \$foo == 3\n" }
+	when (/^a[bc]d$/) { print "\$foo eq 'abd' || \$foo eq 'acd'\n" }
+	when ($_ > 100)   { print "\$foo > 100\n" }
+	default		  { print "None of the above\n" }
+    }
+
+=head1 DESCRIPTION
+
+It is usually impossible to add new syntax to Perl without breaking
+some existing programs. This pragma provides a way to minimize that
+risk. New syntactic constructs can be enabled by C<use feature 'foo'>,
+and will be parsed only when the appropriate feature pragma is in
+scope.
+
+=head2 The 'switch' feature
+
+C<use feature 'switch'> tells the compiler to enable the Perl 6
+given/when construct from here to the end of the enclosing BLOCK.
+
+See L<perlsyn/"Switch statements"> for details.
+
+=head2 The '~~' feature
+
+C<use feature '~~'> tells the compiler to enable the Perl 6
+smart match C<~~> operator from here to the end of the enclosing BLOCK.
+
+See L<perlsyn/"Smart Matching in Detail"> for details.
+
+=head2 The 'say' feature
+
+C<use feature 'say'> tells the compiler to enable the Perl 6
+C<say> function from here to the end of the enclosing BLOCK.
+
+See L<perlfunc/say> for details.
+
+=cut
+
+sub import {
+    $^H |= $feature::hint_bits;	# Need this or %^H won't work
+
+    my $class = shift;
+    if (@_ == 0) {
+	require Carp;
+	Carp->import("croak");
+	croak("No features specified");
+    }
+    while (@_) {
+	my $name = shift(@_);
+	if (!exists $feature{$name}) {
+	    require Carp;
+	    Carp->import("croak");
+	    croak(sprintf('Feature "%s" is not supported by Perl %vd',
+		$name, $^V));
+	}
+	$^H{$feature{$name}} = 1;
+    }
+}
+
+sub unimport {
+    my $class = shift;
+
+    # A bare C<no feature> should disable *all* features
+    for my $name (@_) {
+	if (!exists($feature{$name})) {
+	    require Carp;
+	    Carp->import("croak");
+	    croak(sprintf('Feature "%s" is not supported by Perl %vd',
+		$name, $^V));
+	}
+	else {
+	    delete $^H{$feature{$name}};
+	}
+    }
+
+    if(!@_) {
+	delete @^H{ values(%feature) };
+    }
+}
+
+1;
diff --git a/lib/feature.t b/lib/feature.t
new file mode 100644
index 0000000000..a60644f442
--- /dev/null
+++ b/lib/feature.t
@@ -0,0 +1,10 @@
+#!./perl
+
+BEGIN {
+    chdir 't' if -d 't';
+    @INC = '../lib';
+    $ENV{PERL5LIB} = '../lib';
+}
+
+our $pragma_name = "feature";
+require "../t/lib/common.pl";
diff --git a/lib/overload.pm b/lib/overload.pm
index b189044846..8a07efec69 100644
--- a/lib/overload.pm
+++ b/lib/overload.pm
@@ -422,7 +422,7 @@ The dereference operators must be specified explicitly they will not be passed t
 
 =item * I<Special>
 
-    "nomethod", "fallback", "=",
+    "nomethod", "fallback", "=", "~~",
 
 see L<SPECIAL SYMBOLS FOR C<use overload>>.
 
@@ -517,6 +517,11 @@ The key C<"fallback"> governs what to do if a method for a particular
 operation is not found.  Three different cases are possible depending on
 the value of C<"fallback">:
 
+=head2 Smart Match
+
+The key C<"~~"> allows you to override the smart matching used by
+the switch construct. See L<feature>.
+
 =over 16
 
 =item * C<undef>
diff --git a/lib/warnings.t b/lib/warnings.t
index f23d9e67f8..55e2794c7b 100644
--- a/lib/warnings.t
+++ b/lib/warnings.t
@@ -4,201 +4,7 @@ BEGIN {
     chdir 't' if -d 't';
     @INC = '../lib';
     $ENV{PERL5LIB} = '../lib';
-    require Config; import Config;
-    require './test.pl';
 }
 
-use File::Path;
-use File::Spec::Functions;
-
-$| = 1;
-
-my $Is_MacOS   = $^O eq 'MacOS';
-my $tmpfile = "tmp0000";
-1 while -e ++$tmpfile;
-END {  if ($tmpfile) { 1 while unlink $tmpfile} }
-
-my @prgs = () ;
-my @w_files = () ;
-
-if (@ARGV)
-  { print "ARGV = [@ARGV]\n" ;
-    if ($^O eq 'MacOS') {
-      @w_files = map { s#^#:lib:warnings:#; $_ } @ARGV
-    } else {
-      @w_files = map { s#^#./lib/warnings/#; $_ } @ARGV
-    }
-  }
-else
-  { @w_files = sort glob(catfile(curdir(), "lib", "warnings", "*")) }
-
-my $files = 0;
-foreach my $file (@w_files) {
-
-    next if $file =~ /(~|\.orig|,v)$/;
-    next if $file =~ /perlio$/ && !(find PerlIO::Layer 'perlio');
-    next if -d $file;
-
-    open F, "<$file" or die "Cannot open $file: $!\n" ;
-    my $line = 0;
-    while (<F>) {
-        $line++;
-	last if /^__END__/ ;
-    }
-
-    {
-        local $/ = undef;
-        $files++;
-        @prgs = (@prgs, $file, split "\n########\n", <F>) ;
-    }
-    close F ;
-}
-
-undef $/;
-
-plan tests => (scalar(@prgs)-$files);
-
-
-
-for (@prgs){
-    unless (/\n/)
-     {
-      print "# From $_\n";
-      next;
-     }
-    my $switch = "";
-    my @temps = () ;
-    my @temp_path = () ;
-    if (s/^\s*-\w+//){
-        $switch = $&;
-    }
-    my($prog,$expected) = split(/\nEXPECT\n/, $_);
-    my ($todo, $todo_reason);
-    $todo = $prog =~ s/^#\s*TODO(.*)\n//m and $todo_reason = $1;
-    if ( $prog =~ /--FILE--/) {
-        my(@files) = split(/\n--FILE--\s*([^\s\n]*)\s*\n/, $prog) ;
-	shift @files ;
-	die "Internal error test $test didn't split into pairs, got " .
-		scalar(@files) . "[" . join("%%%%", @files) ."]\n"
-	    if @files % 2 ;
-	while (@files > 2) {
-	    my $filename = shift @files ;
-	    my $code = shift @files ;
-    	    push @temps, $filename ;
-    	    if ($filename =~ m#(.*)/#) {
-                mkpath($1);
-                push(@temp_path, $1);
-    	    }
-	    open F, ">$filename" or die "Cannot open $filename: $!\n" ;
-	    print F $code ;
-	    close F or die "Cannot close $filename: $!\n";
-	}
-	shift @files ;
-	$prog = shift @files ;
-    }
-
-    # fix up some paths
-    if ($^O eq 'MacOS') {
-	$prog =~ s|require "./abc(d)?";|require ":abc$1";|g;
-	$prog =~ s|"\."|":"|g;
-    }
-
-    open TEST, ">$tmpfile" or die "Cannot open >$tmpfile: $!";
-    print TEST q{
-        BEGIN {
-            open(STDERR, ">&STDOUT")
-              or die "Can't dup STDOUT->STDERR: $!;";
-        }
-    };
-    print TEST "\n#line 1\n";  # So the line numbers don't get messed up.
-    print TEST $prog,"\n";
-    close TEST or die "Cannot close $tmpfile: $!";
-    my $results = runperl( switches => [$switch], stderr => 1, progfile => $tmpfile );
-    my $status = $?;
-    $results =~ s/\n+$//;
-    # allow expected output to be written as if $prog is on STDIN
-    $results =~ s/tmp\d+/-/g;
-    if ($^O eq 'VMS') {
-        # some tests will trigger VMS messages that won't be expected
-        $results =~ s/\n?%[A-Z]+-[SIWEF]-[A-Z]+,.*//;
-
-        # pipes double these sometimes
-        $results =~ s/\n\n/\n/g;
-    }
-# bison says 'parse error' instead of 'syntax error',
-# various yaccs may or may not capitalize 'syntax'.
-    $results =~ s/^(syntax|parse) error/syntax error/mig;
-    # allow all tests to run when there are leaks
-    $results =~ s/Scalars leaked: \d+\n//g;
-
-    # fix up some paths
-    if ($^O eq 'MacOS') {
-	$results =~ s|:abc\.pm\b|abc.pm|g;
-	$results =~ s|:abc(d)?\b|./abc$1|g;
-    }
-
-    $expected =~ s/\n+$//;
-    my $prefix = ($results =~ s#^PREFIX(\n|$)##) ;
-    # any special options? (OPTIONS foo bar zap)
-    my $option_regex = 0;
-    my $option_random = 0;
-    if ($expected =~ s/^OPTIONS? (.+)\n//) {
-	foreach my $option (split(' ', $1)) {
-	    if ($option eq 'regex') { # allow regular expressions
-		$option_regex = 1;
-	    }
-	    elsif ($option eq 'random') { # all lines match, but in any order
-		$option_random = 1;
-	    }
-	    else {
-		die "$0: Unknown OPTION '$option'\n";
-	    }
-	}
-    }
-    die "$0: can't have OPTION regex and random\n"
-        if $option_regex + option_random > 1;
-    my $ok = 1;
-    if ( $results =~ s/^SKIPPED\n//) {
-	print "$results\n" ;
-    }
-    elsif ($option_random)
-    {
-        $ok = randomMatch($results, $expected);
-    }
-    elsif (($prefix  && (( $option_regex && $results !~ /^$expected/) ||
-			 (!$option_regex && $results !~ /^\Q$expected/))) or
-	   (!$prefix && (( $option_regex && $results !~ /^$expected/) ||
-			 (!$option_regex && $results ne $expected)))) {
-        my $err_line = "PROG: $switch\n$prog\n" .
-                       "EXPECTED:\n$expected\n" .
-                       "GOT:\n$results\n";
-        if ($todo) {
-            $err_line =~ s/^/# /mg;
-            print $err_line;  # Harness can't filter it out from STDERR.
-        }
-        else {
-            print STDERR $err_line;
-        }
-        $ok = 0;
-    }
-
-    $TODO = $todo ? $todo_reason : 0;
-    ok($ok);
-
-    foreach (@temps)
-	{ unlink $_ if $_ }
-    foreach (@temp_path)
-	{ rmtree $_ if -d $_ }
-}
-
-sub randomMatch
-{
-    my $got = shift ;
-    my $expected = shift;
-
-    my @got = sort split "\n", $got ;
-    my @expected = sort split "\n", $expected ;
-
-   return "@got" eq "@expected";
-
-}
+our $pragma_name = "warnings";
+require "../t/lib/common.pl";