Perl print out all subs arguments at every call at runtime - perl

Question

I'm looking for way to debug print each subroutine call from the namespace Myapp::* (e.g. without dumping the CPAN modules), but without the need edit every .pm file manually for to inserting some module or print statement.
I just learning (better to say: trying to understand) the package DB, what allows me tracing the execution (using the shebang #!/usr/bin/perl -d:Mytrace)
package DB;
use 5.010;
sub DB {
my( $package, $file, $line ) = caller;
my $code = \#{"::_<$file"};
print STDERR "--> $file $line $code->[$line]";
}
#sub sub {
# print STDERR "$sub\n";
# &$sub;
#}
1;
and looking for a way how to use the sub call to print the actual arguments of the called sub from the namespace of Myapp::*.
Or is here some easier (common) method to
combine the execution line-tracer DB::DB
with the Dump of the each subroutine call arguments (and its return values, if possible)?

Answer 1

I don't know if it counts as "easier" in any sane meaning of the word, but you can walk the symbol table and wrap all functions in code that prints their arguments and return values. Here's an example of how it might be done:
#!/usr/bin/env perl
use 5.14.2;
use warnings;
package Foo;
sub first {
my ( $m, $n ) = #_;
return $m+$n;
}
sub second {
my ( $m, $n ) = #_;
return $m*$n;
}
package main;
no warnings 'redefine';
for my $k (keys %{$::{'Foo::'}}) {
my $orig = *{$::{'Foo::'}{$k}}{CODE};
$::{'Foo::'}{$k} = sub {
say "Args: #_";
unless (wantarray) {
my $r = $orig->(#_);
say "Scalar return: $r";
return $r;
}
else {
my #r = $orig->(#_);
say "List return: #r";
return #r
}
}
}
say Foo::first(2,3);
say Foo::second(4,6);