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Postings from June 2020
On Sat, 27 Jun 2020 10:47:40 -0700
Karen Etheridge <perl@froods.org> wrote:
> catch my $e {
> if ($e isa X::SomeException) { ... }
> elsif ($e =~ m/^Cannot do a thing/) { ... }
> else { ... }
Ah; but this "..." is exactly the part I'm interested in. What "..."
code do you put there?
If there was a syntax for core's catch mechanism to realise that you
weren't interested in this particular exception, then it can keep
unwinding the stack until it finds a different set of try/catch blocks
from some higher-up caller to invoke instead.
This is why I would really like a core try/catch to have typed
dispatch. It is not *simply* to assist you not having to do the
if/elsif dispatch yourself. It adds a whole new semantic ability of
*not* catching an exception and letting your caller handle it instead.
try { someweirdfunc() }
catch (isa X::MyOwnExceptionType) { ... }
If someweirdfunc throws anyone else's exception object, or not an
exception object at all but just a bare string, the code behaves as if
this `try` never saw it. We keep just propagating up to the caller.
Imagine never having to type
else { die $@ }
ever again. We don't want to re-throw exceptions, we want to not catch
them in the first place.
--
Paul "LeoNerd" Evans
leonerd@leonerd.org.uk | https://metacpan.org/author/PEVANS
http://www.leonerd.org.uk/ | https://www.tindie.com/stores/leonerd/
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