Craig Francis wrote on 09/09/2015 16:54:
I don't think it is an odd thing to suppress a warning for a plain variable.
For example, on a blog you may have a list of articles, which is used by both
the admin and users, but the (MVC) controller might set an $add_url, so a link
to add a new article can be displayed...
Controller:
if (IS_ADMIN) {
$this->set('add_url', '/admin/articles/add/');
}
View:
<?php if (exists($add_url)) { ?>
<p><a href="<?= html($add_url) ?>">Add article</a>
<?php } ?>
I can see that this makes nice terse View code, and is a reasonable use
of existing isset() - though I can't see it needs to be anything other
than isset(), because if $add_url was null, you wouldn't want to echo
anything.
Arguably, it would be better handled with the vars placed into an array
rather than materialising as PHP variables. The helper functions defined
by the framework (here assumed to be called exists() and html()) could
then extract items from that array, making it just as succinct:
<?php if (exists('add_url')) { ?>
<p><a href="<?= html('add_url') ?>">Add article</a>
<?php } ?>
Boom, no more worries about undefined variables.
I'm pretty sure this is how templating languages like Smarty and Twig
work - "{$foo}" in Smarty compiles to something like "echo
$this->vars['foo'];"
Presumably under the hood, the set() method in your example has to
instead do some magic with variable variables - $$foo syntax - which is
like the ugly cousin of an associative array. Either that, or eval(),
which as everyone knows is evil()! :P
But, the thing that wins it over for me is that isset() seems to be (mis)used
by a lot of developers as a function to check if the variable exists (not that
the variable has a value).
Do you mean that it is misused with arrays? Because with plain variables
it does exactly what it needs to do.
Or do you mean that developers are using unset() to represent a state
distinct from null? Because if so, that is their mistake, not the
subsequent use of isset(). I have yet to see a single use case where
distinguishing between these two states is necessary or sensible.
Actually, in a few years time, if developers did their NULL checks with "===
NULL", then isset(), is_null(), array_key_exists(), and empty() could all be
deprecated :-)
- is_null() makes sense because it's a type-checking function: it goes
with is_bool(), is_int(), etc.
- empty() is a bit odd because it's basically an inverted boolean cast,
but does make quite readable code.
- You've just demonstrated yourself a situation where isset() can't be
replaced with === null or is_null() because you want to suppress the
Notice.
- I am fundamentally opposed to a function which distinguishes between
unset($foo) and $foo=null for reasons I have stated several times.
So the only thing left is replacing array_key_exists with some nicer
syntax so you can write some_keyword($foo['bar']) rather than
array_key_exists('bar', $foo)
Regards,
--
Rowan Collins
[IMSoP]
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