On 21 March 2015 17:55:32 GMT, "Georges.L" <cont...@geolim4.com> wrote:
>To be honest I had not thought about the bad side of this use, i guess
>it
>could be possible to not return upper than a try/catch block (then
>return a
>fatal error if our code is trying to returns upper than a try/catch
>block).
>
>Now the practical example:
>
>// Code i have the hand on
>function main()
>{
> foo('bar');
> echo "I'm an angel !";
>}
>
>function bar()
>{
> echo "I'm not Evil";
>}
>
>//Code i don't have the hand on (like a MVC core)
>function foo($thing)
>{
> //
> make_love_dont_war();
> call_user_func($thing);
>
> //Do some stuff i don't want to execute
> echo 'evil';
>}
>
>function make_love_dont_war()
>{
> echo 'Make love, dont war.';
>}
>
>You get it ?
Not really, no. In this example, the code you want to skip happens to be all
the code after executing the callback, but what if there was some essential
cleanup there, or the "evil" line was before the callback, not after?
In general, a function should be a reusable, self-contained unit of code, and
as such shouldn't want to know about where it was called from. But in order to
know how many levels to force to return, you need to know how deeply nested you
are, and the expected return type of the function you're jumping out of, as
well as which code you're bypassing by doing so. If someone reuses the
function, or refactors the calling code, some very confusing bugs will result.
Rather than "jump N levels up the call stack", what you maybe want is "jump up
to somewhere labelled X". This is sort of what exceptions do - they jump up the
stack until they find somewhere expecting to handle that condition. The
function throwing the exception doesn't know where it will be caught, so is not
fragile to reuse or refactoring. However, using exceptions for anything other
than error handling is generally frowned upon, because they can lead to hard to
follow logic which would be better off refactored in plain procedural/OO style.
In your example, it's up to the maintainers of the foo() function (e.g.
framework) to make the "evil" optional, by passing in some additional setting,
or allowing the callback to return a special value, or just splitting the work
in such a way that you can access the desired functionality without calling
foo() at all. If it's open source, you could submit a patch, or, worst case,
maintain a fork.
Regards,
--
Rowan Collins
[IMSoP]
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