Over in a review [1] for Bug 1191067, sebastian asks the following
excellent question:
::: mobile/android/base/AccountsHelper.java:127
> (Diff revision 1)
> > + } catch (Exception e) {
>
> This is not related to these reviews and patches or this line in
> particular but I've seen us catching generic exceptions in various places.
> Is this to ensure the callback is triggered at all costs? I'm always afraid
> that this will silently catch all kinds of unchecked exceptions (e.g.
> NullPointerException, ClassCastException, ..) in later iterations. Do we
> have any guidelines in what situations it's okay to do this? Most projects
> seem to discourage you from doing this.
>
I'll answer from my own perspective, but I'd like to get more comments.
For some context, this code is handling a message from chrome-privileged
JavaScript to Java. The message is expected to be triggered from an add-on
-- i.e., I don't control the inputs entirely. In such contexts --
essentially, message handling -- I never want to fail. Given how hard it
can be to handle unchecked Exception-sub classes, and how hard it can be to
sanitize input completely, I err on the side of caution. It would be nice
to differentiate "routine mistake" NPEs from "bad input, need more null
check" NPEs but I often am not fully confident that I haven't made an
error. In this situation, I blanket catch Exception for safety.
I am not aware of guidelines, expectations, or a style guide for Fennec.
What do others do? What do others think we should recommend?
Thanks, sebastian, for an excellent question!
Nick
[1] https://bugzilla.mozilla.org/show_bug.cgi?id=1191067#c25
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