+=head2 C<wrap $name, %opts>
+
+Generates a wrapper that does the same thing as L</recall>, but specialized for a given function. This wrapper can be compiled once for all to avoid calling C<eval> at each run (like L</recall> does). You can still force the prototype by passing C<< { $name => $proto } >> as the first argument. Others arguments are seen as key / value pairs and tune the code generated by L</wrap>. Valid keys are :
+
+=over 4
+
+=item C<< ref => $func >>
+
+Specifies the function used in the generated code to test the reference type of scalars. Defaults to C<'ref'>. You may also want to use C<Scalar::Util::reftype>.
+
+=item C<< wrong_ref => $code >>
+
+The code executed when a reference of incorrect type is encountered. The result of this snippet is also the result of the generated code, hence it defaults to C<'undef'>. It's a good place to C<croak> or C<die> too.
+
+=item C<< sub => $bool >>
+
+Encloses the code into a C<sub { }> block. Default is true.
+
+=item C<< compile => $bool >>
+
+Makes L</wrap> compile the code generated and return the resulting code reference. Implies C<< sub => 1 >>. Be careful that in this case C<ref> must be a fully qualified function name. Defaults to false.
+
+=back
+
+This is how you make your own C<push> that pushes into array references :
+
+ my @a = (0 .. 2);
+ my $push = wrap 'CORE::push', compile => 1;
+ $push->(\@a, 3 .. 7); # returns 3 + 5 = 8, and @a now contains 0 .. 7
+
+=cut
+
+sub _wrap {
+ my ($name, $proto, $i, $args, $cr, $opts) = @_;
+ if ($proto =~ /(\\?)(\[[^\]]+\]|[^\];])(.*)/g) {
+ my ($ref, $p) = ($1, $2);
+ $proto = $3;
+ $p = $1 if $p =~ /^\[([^\]]+)\]/;
+ if ($ref) {
+ if (length $p > 1) {
+ return 'my $r = ' . $opts->{ref} . '($_[' . $i . ']); '
+ . join ' els',
+ map( {
+ "if (\$r eq '" . $reftypes{$_} ."') { "
+ . _wrap($name, $proto, ($i + 1),
+ $args . $_ . '{$_[' . $i . ']}, ',
+ $cr, $opts)
+ . ' }'
+ } split //, $p),
+ 'e { ' . $opts->{wrong_ref} . ' }'
+ } else {
+ $args .= $p . '{$_[' . $i . ']}, ';
+ }
+ } elsif ($p =~ /[\@\%]/) {
+ $args .= '@_[' . $i . '..$#_]';
+ } elsif ($p =~ /\&/) {
+ my %h = do { my $c; map { $_ => $c++ } @$cr };
+ my $j;
+ if (not exists $h{$i}) {
+ push @$cr, $i;
+ $j = $#{$cr};
+ } else {
+ $j = int $h{$i};
+ }
+ $args .= 'sub{&{$c[' . $j . ']}}, ';
+ } elsif ($p eq '_') {
+ $args .= '((@_ > ' . $i . ') ? $_[' . $i . '] : $_), ';
+ } else {
+ $args .= '$_[' . $i . '], ';
+ }
+ return _wrap($name, $proto, ($i + 1), $args, $cr, $opts);
+ } else {
+ $args =~ s/,\s*$//;
+ return $name . '(' . $args . ')';
+ }
+}
+
+sub wrap {
+ my ($name, $proto) = _check_name shift;
+ croak 'Optional arguments must be passed as key => value pairs' if @_ % 2;
+ my %opts = @_;
+ $opts{ref} ||= 'ref';
+ $opts{sub} = 1 if not exists $opts{sub} or $opts{compile};
+ $opts{wrong_ref} = 'undef' if not defined $opts{wrong_ref};
+ my @cr;
+ my $call;
+ if (defined $proto) {
+ $call = _wrap $name, $proto, 0, '', \@cr, \%opts;
+ } else {
+ $call = _wrap $name, '', 0, '@_';
+ }
+ if (@cr) {
+ $call = 'my @c; '
+ . join('', map { 'push @c, $_[' . $_ . ']; ' } @cr)
+ . $call
+ }
+ $call = '{ ' . $call . ' }';
+ $call = 'sub ' . $call if $opts{sub};
+ $call = eval $call if $opts{compile};
+ return $call;
+}
+