[Koha-devel] Coding patterns discussion

[Jonathan Druart]

Hi,

We used to have problems with transactions, if they were used from the
a subroutine/method which was called from tests (which use
transactions as well), it did not work.
Two transactions could not be started together.
Now that we are using DBIx::Class transactions it works correctly and
we will be able to use it in the codebase everywhere we need it.
I try to use it as soon as it's useful (see
Koha::Acquisition::Currency->store and bug 16907
Koha::Patrons->delete).

Regarding the try-catch module, the following is fine by me:
use Koha::Exceptions;
use Try::Tiny;
sub boom {
    Koha::Exceptions::Exception->throw;
}
try {
    boom();
} catch {
    if ( ref($_) eq 'Koha::Exceptions::Exception' ) {
        # Do that
    } elsif ( ref($_) eq 'Koha::Exceptions::AnotherException' ) {
        # do something else
    }
}

Not very different from the TryCatch syntax, we just have 1 more level
of indent.
You should also have a look at Bug 13995 - Proper Exception handling

Cheers,
Jonathan

2016-09-12 19:32 GMT+01:00 Tomas Cohen Arazi <tomascohen at gmail.com>:
> I've been looking at our coding patterns, and noticed we haven't
> discussed/agreed on some stuff. Which is a good oportunity to just do it,
> now the Koha:: namespace is being filled with cool old-code rewrites with
> lots of test coverage.
>
> - Transactions on heavy business functions that should definitely be wrapped
> inside a transaction.
>
> Running
>   $ cd Koha ; git grep txn
> is just sad.
>
> - Little use of Exceptions in Koha. We introduced them, but still don't
> extend its use. Maybe related to the next item.
>
> I think we should keep general exceptions (like
> Koha::Exceptions::ObjectNotFound) in the general Koha::Exceptions namespace.
> But move the package-specific ones into its own file. To aid maintenance. A
> good candidate are Koha::Exceptions::Virtualshelves
>
> - We don't use a Try/Catch library. It would make it easier to use
> Koha::Exceptions with a nice syntax.
>
> There are a couple interesting libraries: Try::Tiny and TryCatch. [1] I
> prefer the latter because the type check seems nicer to write and eval
> (instead of an if/ifelse cascade checking ref($exception) eq 'Something'.
>
> I have my opinions on this items, and it would be great to discuss it
> openly. There's code in bugzilla waiting for QA, and it'd be great to have
> some consensus on how to organize the code for the future.
>
> Regards
>
> [1] http://search.cpan.org/~ether/Try-Tiny-0.27/lib/Try/Tiny.pm and
> http://search.cpan.org/~ash/TryCatch-1.003002/lib/TryCatch.pm
>
> --
> Tomás Cohen Arazi
> Theke Solutions (https://theke.io)
> ✆ +54 9351 3513384
> GPG: B2F3C15F
>
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