what are the disadvantages of using the perl debugger vs a real REPL like Devel::REPL?

Question

Hello, I usually use perl -de 42 for obtaining an interactive perl shell. I have seen Devel::REPL and I have seen some blogs like http://www.xenoterracide.com/2010/07/making-repl-usable.html explaining how you can enhance Devel::REPL with the plugins, but I have not used yet.

I am wondering: is it too bad to use the debugger as an interactive shell? why?

note: the disadvantages mention in this perlmonks node were limitations of the user not of the perl debugger.

Do someone know where I can read more about perl REPL?

Is Devel::REPL ready for limelight?

UPDATE: I accepted the Pedro's answer because it answered the question that I asked, but still I would like to know when and why (if any) the use of the perl debugger as an interactive shell is a bad idea compared with one of the perl REPL implementations. And which perl REPL do you prefer?

Answer 1

One disadvantage of perl -d is that lexical variables immediately go out of scope. Example:

DB<1> my $p = 123;

DB<2> print $p;

DB<3>

From perldebug:

Note that the said eval is bound by an implicit scope. As a result any newly introduced lexical variable or any modified capture buffer content is lost after the eval. The debugger is a nice environment to learn Perl, but if you interactively experiment using material which should be in the same scope, stuff it in one linescope, stuff it in one line.

Answer 2

Rather than use the debugger and miss out on features, I tend to use just

perl -wnE'say eval()//$@'

I've used Devel::REPL and like it, but just never got used to using it.

An advantage to using the debugger is being able to have $DB::single=1 to stop and single-step at a given point.

Answer 3

Both have different goals. The debugger is optimised for debugging an already written Perl script/program. Whereas a REPL primary objective is to provide quick language feedback and is optimised for (the developers) interactive input.

For eg. If I do the following in the Perl debugger:

DB<1> for my $x (1..10) {

I get a Missing right curly or square bracket at (eval 5)... error.

Whereas with Devel::REPL it allows multiple line input:

$ for my $x (1..3) {
> say $x;
> }
1
2
3

I thoroughly recommend Devel::REPL and with the extra plugins it becomes a handy development tool to have running beside your editor.

/I3az/