pre-install and post-install hooks for Type::Params

Author: tobyink

lib/Type/Params.pm

@@ -184,10 +184,21 @@ sub signature_for {
 		goto( $compiled );
 	};
 
+	our ( %PRE_INSTALL, %POST_INSTALL );
+	if ( my $cb = $PRE_INSTALL{$package} ) {
+		Types::Standard::assert_ArrayRef( $cb );
+		$_->( $sig ) for @$cb;
+	}
+
 	no strict 'refs';
 	no warnings 'redefine';
 	*$fullname = set_subname( SIGNATURE_SUBNAME_PREFIX . $fullname . SIGNATURE_SUBNAME_SUFFIX, $coderef );
 
+	if ( my $cb = $POST_INSTALL{$package} ) {
+		Types::Standard::assert_ArrayRef( $cb );
+		$_->( $sig ) for @$cb;
+	}
+
 	return $sig;
 }
 
@@ -2036,6 +2047,27 @@ Example usage:
 
 =back
 
+=head1 HOOKS
+
+You can install coderefs which will be called whenever C<signature_for>,
+C<signature_for_func>, or C<signature_for_method> are used to wrap a
+function or method. They are ignored by C<signature> and by the pre-v2 API.
+
+  push @{ $Type::Params::POST_INSTALL{'My::Package'} ||= [] }, sub {
+    my $signature = shift;
+    ...;
+  };
+
+  push @{ $Type::Params::PRE_INSTALL{'My::Package'} ||= [] }, sub {
+    my $signature = shift;
+    ...;
+  };
+
+The C<< $signature >> will be a blessed L<Type::Params::Signature> object.
+
+The intention for this is to allow for future extensions to expose signature
+data as metadata. 
+
 =head1 BUGS
 
 Please report any bugs to

t/20-modules/Type-Params/v2-hooks.t

@@ -0,0 +1,47 @@
+=pod
+
+=encoding utf-8
+
+=head1 PURPOSE
+
+Test the pre-install and post-install hooks.
+
+=head1 AUTHOR
+
+Toby Inkster E<lt>tobyink@cpan.orgE<gt>.
+
+=head1 COPYRIGHT AND LICENCE
+
+This software is copyright (c) 2025 by Toby Inkster.
+
+This is free software; you can redistribute it and/or modify it under
+the same terms as the Perl 5 programming language system itself.
+
+=cut
+
+use strict;
+use warnings;
+use Test::More;
+
+my @GOT;
+
+push @{ $Type::Params::PRE_INSTALL{'Local::Foo'} ||= [] }, sub {
+	my $signature = shift;
+	push @GOT, pre => $signature->subname;
+};
+
+push @{ $Type::Params::POST_INSTALL{'Local::Foo'} ||= [] }, sub {
+	my $signature = shift;
+	push @GOT, post => $signature->subname;
+};
+
+{
+	package Local::Foo;
+	use Types::Common -all;
+	signature_for bar => ( pos => [] );
+	sub bar { return 'bar' };
+}
+
+is_deeply( \@GOT, [ qw/ pre bar post bar / ] );
+
+done_testing;