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Motivation¶

Using modern builtin perl features

https://metacpan.org/pod/Feature::Compat::Try is a module that provides the same
interface and functionality as the new try feature for older perl versions (<
5.34.0).

It automaticallly uses the builtin try feature for perl >= 5.34.0

use Feature::Compat::Try;

# In perl 5.34.0 same as:
use experimental 'try';

# Leap 16 will have perl 5.38, so as soon as we can make
# perl 5.38 the minimum version, we would write:
use v5.36; # strict, warnings, signatures, ...
use experimental 'try';

# With perl 5.40 it would be just:
use v5.40; # strict, warnings, signatures, try, ...

The basic try/catch feature got non-experimental with 5.40, so it's safe to
use.
The finally part is still experimental, so theoretically implementation
changes could happen.
The feature is tracked here: https://github.com/Perl/perl5/issues/18760

Example Feature::Compat::Try vs. eval and Try::Tiny¶

Feature::Compat::Try¶

use v5.12;
use warnings;
use experimental 'signatures';
use Feature::Compat::Try;

sub foo ($fail) {
    try {
        say "trying";
        die "oops" if $fail;
        return "pass"; # returns from foo()
    }
    catch ($e) {
        warn "Exception: $e";
        return "fail"; # returns from foo()
    }
    finally {
        say "whatever happens, I'm here";
    }
    say "end of subroutine"; # not reached
}

say foo(0);
say foo(1);

Try::Tiny¶

use v5.12;
use warnings;
use experimental 'signatures';
use Try::Tiny;

sub foo ($fail) {
    my $res;
    try {
        say "trying";
        die "oops" if $fail;
        $res = "pass";
        return "pass"; # does not return from foo()
    }
    catch {
        warn "Exception: $_";
        $res = "fail";
        return "fail"; # does not return from foo()
    }
    finally {
        say "whatever happens, I'm here";
    };
    return $res;
}

say foo(0);
say foo(1);

Pro¶

• In Leap >= 15.5

Compared to Try::Tiny:

• Future builtin
• Can return from subroutine
• catch ($some_name) instead of $_
• Real block syntax element{} - no ; at the end needed

Con¶

• Still partially experimental in 5.40