Out of curiosity, what's an actual example of code where the execution flow
of exceptions is significantly more surprising than the execution flow of a
billion manual checks to avoid "Fatal error: Call to a member function
foo() on a non-object"?
I've heard the vague claim that exceptions are confusing for years, but for
the life of me I've never seen exception-handling code that looked more
complex or confusing than code riddled with checks for magic return values.
-- brion
On Mon, Oct 7, 2013 at 11:20 AM, Erik Bernhardson <
ebernhardson(a)wikimedia.org> wrote:
Within mediawiki there is a split between returning
false/null and throwing
exceptions. There is also the Status class used by the wikitext parser(the
Status class is somewhat closely tied to the parser reducing reusability
though). essentially there are 3 kinds of error handling used within
mediaiki.
We talked amongst the Flow team and agreed that we prefer false/null over
exceptions, mostly due to issues where exceptions can short-circuit the
expected execution path just about everywhere in a non-obvious manner(a big
enough issue that java uses checked exceptions, another world of pain).
During code review we spend a reasonable amount of time just ensuring that
functions that can return false/null are actually checked.
Moving forward, the Flow team is considering using a php implementation
that follows the ideas of the haskell Maybe monad(
https://github.com/schmittjoh/php-option ). This is, in concept, rather
similar to the Status class the wikitext parser returns. We would like to
use this library as a way to more explicitly handle error situations and
reduce the occurrences of forgetting to check false/null. This particular
pattern is very common in Functional languages.
I do believe this method of error handling is friendlier to programmers
memory, easier to code review, and more explicit about what happens in the
error condition. Are there any concerns with the Flow project moving
forward and utilizing this as our primary error handling mechanism rather
than returning false/null?
Erik B.
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