[development] Multiple strings with same translation may break form functionality

[lodewijk evers]

Today I spent a lot of time tracking why a form did not work and found an
issue with translations and a commonly used way of validating forms.

In a site with german localization and ecommerce modules I translated a lot
of the form submit buttons strings in the checkout process into a generic
label "Weiter" (Next in German) and I broke the process.
*Why?*
Because the "$op" operator is frequently used to check if an action should
be performed in a similar way to:
<?php switch ($op) { case t('Do something'): ... } ?>
And if the translation for 'Do something' just happens to be the same like
the translation for another form button in the same series of forms you can
guess why it's not working... In my case it was validating an address with
the formdata for a shopping cart, and barfed.

I don't know if this issue is solved in the forms API for 4.7+ but if it
isn't we should look into that.
For 4.6 it might be wise to use translations with caution.

Regards,

Lodewijk Evers

Ontwerpwerk
multdisciplinary design
l.evers at ontwerpwerk.nl
http://www.ontwerpwerk.nl