Le Fri, 18 Sep 2015 20:38:12 +0200, Rowan Collins
<rowan.coll...@gmail.com> a écrit:
Benoit Schildknecht wrote on 18/09/2015 19:24:
I agree. exists() would allow PHP devs to make more secure, cleaner and
lighter code. It fills a gap and would be useful to a lot of devs.
On the contrary, I think code using exists() would be extremely fragile,
because it's highly resistant to refactoring, and encourages developers
to leave variables uninitialised.
What makes cleaner, more secure code is always initialising your
variables before using them - basically, what the "undefined variable"
Notice is suggesting you do.
The examples Lester and Robert have come up with make sense in
themselves, but are not architectures I would choose precisely because
they are opaque (you have to remember what unset() and null mean) and
hard to extend (there's no way to introduce a 4th state alongside the
unset/null/value triad).
Obviously, all language features can be used to write bad code, but it
seems much easier to write bad code than good using this proposed
function.
Regards,
So there is a bug regarding variables and null. Because I don't get any
notice if I use a variable with "null" as a value. If "null" means
"uninitialized", how come there are no notices ?
<?php
echo $foo;//Notice
$foo = null;
echo $foo;//No Notice
And how come the null variable appear in get_defined_vars(), and disappear
after an unset() ? Because null != undefined. The engine seems to consider
null as a distinct state. Something that is not undefined. It is already
like that, we are not theorizing.
<?php
var_dump(get_defined_vars()); // No traces of $foo
$foo = null;
var_dump(get_defined_vars()); // ["foo"] => NULL
unset($foo);
var_dump(get_defined_vars()); // Good bye, foo
You have a lot of people who use isset() against null elements in an
array. null elements happen a lot when interacting with an SQL server (for
instance). I personally use array_key_exists(), but most people won't do
the same at all. Because they think it is the same. And they'll forget,
because isset() behaviour doesn't make sense, since null doesn't exactly
behave as you say.
Using is_null() against a var to see if it is set and has a null value
WILL trigger notices, and that's clearly not clean at all. In a production
environment, you would like to get rid of them. All of them.
Taking advantage of set_error_handler() is out of question : how can you
know if the triggered notice is related to a variable you expected to be
declared with null ? Very hard task (if not impossible), and very heavy to
implement.
And you have webservices, cURL, JSON, etc... All of these can give you
"null" values. And it is not rare. This is not something we can correct.
We have no control on this.
There are way more cases in which exists() would improve things A LOT. We
need a native function that allows us to check this state WITHOUT
triggering a notice.
Regards,
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