TryCatch(3pm)

💖 TryCatch 💖

ok so bestie, welcome to TryCatch — it's a Perl module from the User Contributed Perl Documentation crew, and it's literally here to give you first class try/catch semantics without any source filters. no cap. 🎀

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✨ NAME ✨

TryCatch — first class try catch semantics for Perl, without source filters. periodt. 💅

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🌸 DESCRIPTION 🌸

okay so here's the vibe: this module wants to hand you a nicer syntax and a nicer method for catching errors in Perl, kinda like what other languages have going on — think Java, Python, or C++. 🦋

and the way we usually do it, eval {}; if ($@) {}? yeah... that idiom is often prone to subtle bugs, mostly because it's way too easy to stomp on the error while you're inside your error handlers. 😭 also, not gonna lie, eval/if just isn't the cutest idiom. it's giving chaos. this module is giving main character energy instead. 👑

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⭐ SYNOPSIS ⭐

use TryCatch;

sub foo {
  my ($self) = @_;

  try {
    die Some::Class->new(code => 404 ) if $self->not_found;
    return "return value from foo";
  }
  catch (Some::Class $e where { $_->code > 100 } ) {
  }
}

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🧚 SYNTAX 🧚

so the whole goal here is to give perl first class exception handling via the 'try' and 'catch' keywords. the basic syntax is try { # block }, followed by zero or more catch blocks. each catch block can carry an optional type constraint on it, and it lowkey resembles Perl6's method signatures. 🌈

also super worth noting: the error variable ($@) is localised to the try/catch blocks. so it will not leak outside the scope, and it will not stomp on a previous value of $@. obsessed. 🫶

the simplest case of a catch block is just

catch { ... }

where, upon the error, everything's chillin' in the standard $@ variable and no type checking is performed. if you'd rather grab the exception through a named lexical variable instead, just hand the catch block a simple signature like this:

catch ($err) { ... }

and if you want type checking on the exception? you can do that by specifying a type constraint or where clauses in the signature, like so:

catch (TypeFoo $e) { ... }
catch (Dict[code => Int, message => Str] $err) { ... }

as you can see from the above, complex Moose types are totally allowed, including the MooseX::Types style of type constraints. 💜

beyond type checking via Moose type constraints, you can also use where clauses to only match a certain sub-condition on an error. for example — assuming HTTPError is a suitably defined TC:

catch (HTTPError $e where { $_->code >= 400 && $_->code <= 499 } ) {
  return "4XX error";
}
catch (HTTPError $e) {
  return "other http code";
}

that would return "4XX error" for a 404, and "other http code" for a 302. slay. 🔥

and when multiple catch blocks are present? the first one that matches the type constraints (if there are any) gets executed. first come, first served, bestie. 💅

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👑 BENEFITS 👑

• return. you can put a return inside a try block and it does the right thing — namely, it returns a value from the subroutine you're actually in, instead of just from the eval block. iconic behaviour fr fr. ✨
• Type Checking. this is nothing you couldn't do manually yourself — it just does it for you using Moose type constraints. 🎀

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💀 TODO 💀

1. Decide on "finally" semantics w.r.t return values.
1. Write some more documentation
1. Split out the dependancy on Moose

not me leaving the Moose dependancy splitting for later 🙈 it's on the list, bestie, it's on the list.

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🌟 SEE ALSO 🌟

• MooseX::Types
• Moose::Util::TypeConstraints
• Parse::Method::Signatures

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💖 AUTHOR 💖

Ash Berlin <ash@cpan.org>

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🫶 THANKS 🫶

• Thanks to Matt S Trout and Florian Ragwitz for work on Devel::Declare and various B::Hooks modules
• Vincent Pit for Scope::Upper that makes the return from block possible.
• Zefram for providing support and XS guidance.
• Xavier Bergade for the impetus to finally fix this module in 5.12.

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🎀 LICENSE 🎀

Licensed under the same terms as Perl itself.

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and that's the whole page, bestie 💜 this one's running on perl v5.40.1 and it was dated 2025-04-15 — go forth and catch those exceptions with main character energy, iykyk 🌈✨💅