Tom Worster wrote:
On 9/12/09 9:50 AM, "Tom Worster" <fsb@xxxxxxxxxx> wrote:
On 9/12/09 1:32 AM, "Lars Torben Wilson" <torben@xxxxxxx> wrote:
Tom Worster wrote:
if i have an expression that evaluates to an object, the return value from a
function, say, and i only want the value of one of the objects properties,
is there a tidy way to get it without setting another variable?
to illustrate, here's something that doesn't work, but it would be
convenient if it did:
$o = array( (object) array('a'=>1), (object) array('a'=>2) );
if ( end($o)->a > 1 ) { // can't use -> like this!
...
}
What version of PHP are you using? Your example should work.
Torben
5.2.9.
what version does it work in?
i shamefully beg your pardon, lars. i was sure i tested the example but it's
clear to me now i either didn't or i made a mistake. end($o)->a IS php
syntax! so -> may follow a function (or method, i guess) call.
No need for apologies. :)
but let me give you a more different example:
$a and $b are normally both objects, each with various members including a
prop q, but sometimes $a is false. i want the q of $a if $a isn't false,
otherwise that of $b.
($a ? $a : $b)->q // is not php, afaik
before you suggest one, i know there are simple workarounds.
You're right, that isn't PHP syntax. One workaround that came to mind
which does
a similar thing (although using a different mechanism) is this:
${$a ? 'a' : 'b'}->q
but mine is a theoretical question about syntax, not a practical one. i'm
exploring php's syntactic constraints on the -> operator in contrast to,
say, the + or . operators. and in contrast to other languages.
I can respect that. This kind of exploration is often quite illuminating.
for example, the . in js seems more generally allowed than -> (or, for that
matter, []) in php. programmers (especially using jquery) are familiar with
using . after an expression that evaluates to an object, e.g.
<body>
<p id="thepara" class="top x23 indent">My x class number is
<span id="num"></span></p>
<div id="mandatory" style="border: solid red 1px"></div>
<script type="text/javascript">
document.getElementById('num').innerText =
( ( document.getElementById('optional')
|| document.getElementById('mandatory')
).appendChild(document.getElementById('thepara'))
.className.match(/x(\d+)/) || [0,'absent']
)[1]
</script>
</body>
which shows . after objects, method calls and expressions (as well as the []
operator applied to an expression).
do we just live without in phpville or am i missing something?
We live without, just like we live without
$foo =~ s/bar/baz/i;
. . .and without:
cout << "Hello " << world << endl;
. . .and without:
#define FOO(bar, baz) ((bar) * (baz))
. . .and so on. It's just syntax from other languages which isn't part
of the PHP syntax.
and while i'm at it, and using my original error, how come...
function o() { return (object) array('q'=>7); }
echo o()->q; // is ok syntax, but
function a() { return array('q'=>5); }
echo a()['q']; // isn't?
I'm afraid I can't answer that right now--it does perhaps seem
inconsistent at first glance,
although I can't say I've ever missed it or felt that using syntax like
that would make my
life any better. Maybe it would. Then again, I can also see an argument
being made for
allowing the object syntax but not the array syntax: in the case of
objects, you can have
a clean class declaration which is pretty much self-documenting, and
later users of the
class can have a clear idea of which properties are available and which
are not, and they
can thus be sure that o()->q will not result in uninitialized property
problems. Using the
array syntax you could never be sure that the index requested actually
exists.
Of course, this holds true only for people like me who don't really like
the idea of creating
objects on the fly in PHP unless there's a very good reason to. Usually
in PHP such tasks
are better handled by arrays anyway.
This is of course just random thinking and perhaps it's just because
nobody has added
that syntax to the scanner. :)
Anyway, good luck with your language comparison. Like I said before,
that kind of thing
is often fun (and always instructional).
Regards,
Torben
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