the kind of perl code that can only be written at 4:30 am

(Get a good message when a PageSpec fails due to a negated success by
creating success objects with a reason string, which morph into failure
objects when negated.)

IkiWiki.pm

@@ -1006,8 +1006,22 @@ sub pagespec_match ($$;@) { #{{{
 package IkiWiki::FailReason;
 
 use overload (
-	'""' => sub { return ${$_[0]} },
+	'""'	=> sub { return ${$_[0]} },
-	'0+' => sub { return 0 },
+	'0+'	=> sub { return 0 },
+	'!'	=> sub { bless $_[0], 'IkiWiki::SuccessReason'},
+	fallback => 1,
+);
+
+sub new {
+	bless \$_[1], $_[0];
+}
+
+package IkiWiki::SuccessReason;
+
+use overload (
+	'""'	=> sub { return ${$_[0]} },
+	'0+'	=> sub { return 1 },
+	'!'	=> sub { bless $_[0], 'IkiWiki::FailReason'},
 	fallback => 1,
 );
 
@@ -1037,7 +1051,7 @@ sub match_glob ($$;@) { #{{{
 	$glob=~s/\\\?/./g;
 
 	if ($page=~/^$glob$/i) {
-		return 1
+		return IkiWiki::SuccessReason->new("$glob matches $page");
 	}
 	else {
 		return IkiWiki::FailReason->new("$glob does not match $page");
@@ -1063,7 +1077,8 @@ sub match_link ($$;@) { #{{{
 	my $bestlink = IkiWiki::bestlink($from, $link);
 	return IkiWiki::FailReason->new("no such link") unless length $bestlink;
 	foreach my $p (@$links) {
-		return 1 if $bestlink eq IkiWiki::bestlink($page, $p);
+		return IkiWiki::SuccessReason->new("$page links to $link")
+			if $bestlink eq IkiWiki::bestlink($page, $p);
 	}
 	return IkiWiki::FailReason->new("$page does not link to $link");
 } #}}}
@@ -1077,10 +1092,15 @@ sub match_created_before ($$;@) { #{{{
 	my $testpage=shift;
 
 	if (exists $IkiWiki::pagectime{$testpage}) {
-		return $IkiWiki::pagectime{$page} < $IkiWiki::pagectime{$testpage};
+		if ($IkiWiki::pagectime{$page} < $IkiWiki::pagectime{$testpage}) {
+			IkiWiki::SuccessReason->new("$page created before $testpage");
+		}
+		else {
+			IkiWiki::FailReason->new("$page not created before $testpage");
+		}
 	}
 	else {
-		return IkiWiki::FailReason->new("$page not created before $testpage");
+		return IkiWiki::FailReason->new("$testpage has no ctime");
 	}
 } #}}}
 
@@ -1089,26 +1109,43 @@ sub match_created_after ($$;@) { #{{{
 	my $testpage=shift;
 
 	if (exists $IkiWiki::pagectime{$testpage}) {
-		return $IkiWiki::pagectime{$page} > $IkiWiki::pagectime{$testpage};
+		if ($IkiWiki::pagectime{$page} > $IkiWiki::pagectime{$testpage}) {
+			IkiWiki::SuccessReason->new("$page created after $testpage");
+		}
+		else {
+			IkiWiki::FailReason->new("$page not created after $testpage");
+		}
 	}
 	else {
-		return IkiWiki::FailReason->new("$page not created after $testpage");
+		return IkiWiki::FailReason->new("$testpage has no ctime");
 	}
 } #}}}
 
 sub match_creation_day ($$;@) { #{{{
-	return 1 if ((gmtime($IkiWiki::pagectime{shift()}))[3] == shift);
+	if ((gmtime($IkiWiki::pagectime{shift()}))[3] == shift) {
-	return IkiWiki::FailReason->new("creation_day did not match");
+		return IkiWiki::SuccessReason->new("creation_day matched");
+	}
+	else {
+		return IkiWiki::FailReason->new("creation_day did not match");
+	}
 } #}}}
 
 sub match_creation_month ($$;@) { #{{{
-	return 1 if ((gmtime($IkiWiki::pagectime{shift()}))[4] + 1 == shift);
+	if ((gmtime($IkiWiki::pagectime{shift()}))[4] + 1 == shift) {
-	return IkiWiki::FailReason->new("creation_month did not match");
+		return IkiWiki::SuccessReason->new("creation_month matched");
+	}
+	else {
+		return IkiWiki::FailReason->new("creation_month did not match");
+	}
 } #}}}
 
 sub match_creation_year ($$;@) { #{{{
-	return 1 if ((gmtime($IkiWiki::pagectime{shift()}))[5] + 1900 == shift);
+	if ((gmtime($IkiWiki::pagectime{shift()}))[5] + 1900 == shift) {
-	return IkiWiki::FailReason->new("creation_year did not match");
+		return IkiWiki::SuccessReason->new("creation_year matched");
+	}
+	else {
+		return IkiWiki::FailReason->new("creation_year did not match");
+	}
 } #}}}
 
 sub match_user ($$;@) { #{{{
@@ -1117,8 +1154,12 @@ sub match_user ($$;@) { #{{{
 	my %params=@_;
 
 	return IkiWiki::FailReason->new("cannot match user") unless exists $params{user};
-	return 1 if $user eq $params{user};
+	if ($user eq $params{user}) {
-	return IkiWiki::FailReason->new("user is not $user");
+		return IkiWiki::SuccessReason->new("user is $user")
+	}
+	else {
+		return IkiWiki::FailReason->new("user is not $user");
+	}
 } #}}}
 
 1

IkiWiki/Plugin/conditional.pm

@@ -62,8 +62,12 @@ sub match_enabled ($$;@) { #{{{
 	my $plugin=shift;
 	
 	# test if the plugin is enabled
-	return 1 if UNIVERSAL::can("IkiWiki::Plugin::".$plugin, "import");
+	if (UNIVERSAL::can("IkiWiki::Plugin::".$plugin, "import")) {
-	return IkiWiki::FailReason->new("$plugin is not enabled");
+		return IkiWiki::SuccessReason->new("$plugin is enabled");
+	}
+	else {
+		return IkiWiki::FailReason->new("$plugin is not enabled");
+	}
 } #}}}
 
 sub match_sourcepage ($$;@) { #{{{
@@ -72,8 +76,12 @@ sub match_sourcepage ($$;@) { #{{{
 	my %params=@_;
 
 	return IkiWiki::FailReason->new("cannot match sourcepage") unless exists $params{sourcepage};
-	return 1 if match_glob($params{sourcepage}, $glob, @_);
+	if (match_glob($params{sourcepage}, $glob, @_)) {
-	return IkiWiki::FailReason->new("sourcepage does not match $glob");
+		return IkiWiki::SuccessReason->new("sourcepage matches $glob");
+	}
+	else {
+		return IkiWiki::FailReason->new("sourcepage does not match $glob");
+	}
 } #}}}
 
 sub match_destpage ($$;@) { #{{{
@@ -82,8 +90,12 @@ sub match_destpage ($$;@) { #{{{
 	my %params=@_;
 	
 	return IkiWiki::FailReason->new("cannot match destpage") unless exists $params{destpage};
-	return 1 if match_glob($params{destpage}, $glob, @_);
+	if (match_glob($params{destpage}, $glob, @_)) {
-	return IkiWiki::FailReason->new("destpage does not match $glob");
+		return IkiWiki::SuccessReason->new("destpage matches $glob");
+	}
+	else {
+		return IkiWiki::FailReason->new("destpage does not match $glob");
+	}
 } #}}}
 
 sub match_included ($$;$) { #{{{
@@ -92,8 +104,12 @@ sub match_included ($$;$) { #{{{
 	my %params=@_;
 
 	return IkiWiki::FailReason->new("cannot match included") unless exists $params{sourcepage} && exists $params{destpage};
-	return 1 if $params{sourcepage} ne $params{destpage};
+	if ($params{sourcepage} ne $params{destpage}) {
-	return IkiWiki::FailReason->new("page $params{sourcepage} is not included");
+		return IkiWiki::SuccessReason->new("page $params{sourcepage} is included");
+	}
+	else {
+		return IkiWiki::FailReason->new("page $params{sourcepage} is not included");
+	}
 } #}}}
 
 1

IkiWiki/Plugin/testpagespec.pm

@@ -16,8 +16,12 @@ sub preprocess (@) { #{{{
 	
 	my $ret=pagespec_match($params{match}, $params{pagespec}, 
 			location => $params{page});
-	return $ret if ! $ret;
+	if ($ret) {
-	return "the pagespec matches";
+		return "match: $ret";
+	}
+	else {
+		return "no match: $ret";
+	}
 } # }}}
 
 1

debian/changelog

@@ -30,10 +30,10 @@ ikiwiki (1.51) UNRELEASED; urgency=low
   * Plugin interface version increased to 2.00 since I don't anticipate any
     more interface changes before 2.0.
   * Updated Gujarati translation from Kartik Mistry. Closes: #421198
-  * Make pagespec_match on failure return a value that is false, but in a
+  * Make pagespec_match return an object that can be stringified to tell 
-    scalar context, evaluates to a reason why the match failed.
+    the reason why the match failed or succeeded.
   * Add testpagespec plugin, which might be useful to see why a pagespec isn't
-    matching something.
+    working as desired.
 
  -- Joey Hess <joeyh@debian.org>  Fri, 27 Apr 2007 03:41:52 -0400
 

doc/plugins/testpagespec.mdwn

@@ -2,11 +2,21 @@
 [[tag type/useful]]
 
 This plugin allows testing a [[PageSpec]] to see if it matches a page, and
-if not, why it fails to match.
+to see the part that matches, or causes the match to fail.
 
-Example use:
+Example uses:
 
 	\[[testpagespec pagespec="foopage and barpage" match="foopage"]]
 
-This will print out something like "barpage does not match foopage",
+This will print out something like "no match: barpage does not match foopage",
 highlighting which part of the [[PageSpec]] is causing the match to fail.
+	
+	\[[testpagespec pagespec="foopage or !bar*" match="barpage"]]
+
+This will print out something like "no match: bar* matches barpage", since the part
+of the [[PageSpec]] that fails is this negated match.
+	
+	\[[testpagespec pagespec="foopage or barpage" match="barpage"]]
+
+This will print out something like "match: barpage matches barpage",
+indicating the part of the [[PageSpec]] that did match.

doc/plugins/write.mdwn

@@ -328,10 +328,6 @@ The most often used is "location", which specifies the location the
 PageSpec should match against. If not passed, relative PageSpecs will match
 relative to the top of the wiki.
 
-If the PageSpec fails to match, it may return a IkiWiki::FailReason object,
-which evaluates to false in a boolean context, but in a string context,
-evaulates to the reason the PageSpec failed to match.
-
 #### `bestlink($$)`
 
 Given a page and the text of a link on the page, determine which
@@ -452,5 +448,5 @@ IkiWiki::PageSpec package, that is named `match_foo`, where "foo()" is
 how it will be accessed in a [[PageSpec]]. The function will be passed
 two parameters: The name of the page being matched, and the thing to match
 against. It may also be passed additional, named parameters. It should return
-true if the match succeeds, and either false or a IkiWiki::FailReason object
+a IkiWiki::SuccessReason object if the match succeeds, or an
-if the match fails.
+IkiWiki::FailReason object if the match fails.

po/ikiwiki.pot

@@ -8,7 +8,7 @@ msgid ""
 msgstr ""
 "Project-Id-Version: PACKAGE VERSION\n"
 "Report-Msgid-Bugs-To: \n"
-"POT-Creation-Date: 2007-04-27 03:55-0400\n"
+"POT-Creation-Date: 2007-04-27 04:24-0400\n"
 "PO-Revision-Date: YEAR-MO-DA HO:MI+ZONE\n"
 "Last-Translator: FULL NAME <EMAIL@ADDRESS>\n"
 "Language-Team: LANGUAGE <LL@li.org>\n"

t/pagespec_match.t

@@ -1,7 +1,7 @@
 #!/usr/bin/perl
 use warnings;
 use strict;
-use Test::More tests => 51;
+use Test::More tests => 52;
 
 BEGIN { use_ok("IkiWiki"); }
 
@@ -25,6 +25,7 @@ ok(pagespec_match("a/b/foo", "./*", location => "a/b"), "relative 2");
 ok(pagespec_match("a/foo", "./*", "a/b"), "relative oldstyle call");
 ok(pagespec_match("foo", "./*", location => "a"), "relative toplevel");
 ok(pagespec_match("foo/bar", "*", location => "baz"), "absolute");
+ok(! pagespec_match("foo", "foo and bar"), "foo and bar");
 
 # The link and backlink stuff needs this.
 $config{userdir}="";