"chaining" an array returned from a function, in case anyone actually cares

NogDog

Instigated by this thread at WebDeveloper.com, I came up with this possibly interesting solution looking for a problem -- in other words, I'd probably never use it, but maybe someone else would?

<?php

function foo()
{
	return array(
		'foo' => 'FOO',
		'bar' => 'BAR'
	);
}

function arr2obj(array $arr)
{
	return (object) $arr;
}

echo arr2obj(foo())->bar;

dalecosp

Thanks ... it's educational. Can you tell me why it's called "chaining"? Is that your own terminology, or a concept I should be, but aren't, familiar with?

bradgrafelman

Can you think of any usage cases? Seems like treating the array as an object just adds a lot of overhead... what's wrong with keeping it as an array?

For example, what happened if you were returning a multi-dimensional array? You'd have to have a bunch of arr2obj() conversions inside your chain which could quickly muddy up the code.

NogDog

It just came up because someone who liked using object/method-chaining wondered if there was some way to do it with an array returned from a function. I.e., in a purely OOP context, you can chain object methods/properties, as long as each is (returns, in the case of a method) an object (with the exception of the last element in the chain, which does not have to be):

$foo = new Foo();
echo $foo->someMethod()->propertyOfThatReturnedObject->methodInThatObject()->propertyOfThisLatestObject;

So, assume "methodInThatObject()" returned an array instead of an object, you cannot do:

$foo = new Foo();
echo $foo->someMethod()->propertyOfThatReturnedObject->methodInThatObject()['some_key'];

You would instead have to do

$foo = new Foo();
$result = $foo->someMethod()->propertyOfThatReturnedObject->methodInThatObject();
echo $result['some_key'];

I'm personally not really concerned about this, I just found it an interesting thought experiment or whatever you want to call it, and was somewhat surprised that my "solution" worked -- but I doubt there would be enough cases where I'd feel it saved me anything, and can be completely avoided by taking a fully OOP approach and dealing with an object instead of an array in the first place.

Weedpacket

bradgrafelman wrote:
Can you think of any usage cases? Seems like treating the array as an object just adds a lot of overhead...

Probably not that much, really - less than, say, casting a string to an integer (it's a hashtable lookup either way).

Mind you, since then (in 5.4) it's become valid to write [font=monospace]foo()['bar'][/font]. No, I haven't used it yet; I've been waiting for [font=monospace]foo()()[/font]. I had a look at adding it myself, but the parser scared me off, and it seems to have scared off others who've tried.

bradgrafelman

Weedpacket;11015003 wrote:
Probably not that much, really - less than, say, casting a string to an integer (it's a hashtable lookup either way).

I suppose I meant overhead for the programmer, not the CPU.

Weedpacket;11015003 wrote:
Mind you, since then (in 5.4) it's become valid to write [font=monospace]foo()['bar'][/font].

I thought I'd seen that before, but a cursory search of the PHP manual didn't turn up anything.

Weedpacket;11015003 wrote:
I've been waiting for [font=monospace]foo()()[/font]. I had a look at adding it myself, but the parser scared me off, and it seems to have scared off others who've tried.

What about this?

traq

Weedpacket;11015003 wrote:
Mind you, since then (in 5.4) it's become valid to write [font=monospace]foo()['bar'][/font].

bradgrafelman;11015009 wrote:
I thought I'd seen that before, but a cursory search of the PHP manual didn't turn up anything.

Function array dereferencing has been added, e.g., [font=monospace]foo()[0][/font]

I haven't used it either, but, oooohhmy, I like the [] short array syntax.
And traits are awesome!

cretaceous

looking at that update to 5.4.0 page I see
<?=
is now permanently enabled regardless of php ini setting on short_open_tag
any comments on if that is good/bad ?
(it just reminds me of very old scripts)
( I thought I wouldn't start a new thread as you experts here will have the most valid opinions on it.. and I kinda think I won't use it anyway)

jeepin81

Don't know if this is useful or not but Rasmus's PHP in 2012 slide show discusses the short syntax.

Weedpacket

The rationale is discussed in https://wiki.php.net/rfc/shortags - it's principally for the benefit of those members of the dev team who are principally designers rather than programmers: [font=monospace]<?=[/font] is much nicer for them when building templates than [font=monospace]<?php echo[/font].

traq

It feels wrong, but since it standardizes things I guess it's a win. In any case, looks fine from my house.

sfullman

as I'm doing more javascript, I quickly realize that javascript's object oriented (right term?) structure is cool for chaining as in somefunction()[0] or the like. And I see you guys are saying that's available in 5.4, so that I will definitely start using! I have never done OOP in PHP and probably never will, but that [] syntax is definitely nice to use.

One subtle but important point is, if what goes on inside of foo() is CPU-intensive, it makes sense to store the object "somewhere" so the second call to it doesn't result in a re-calc if possible. In that sense it doesn't appear to be true OOP because you don't "instantiate" it - but you guys probably already knew that.

By the way, for getting data INTO a function, almost all functions I write now are in the format of:

function dosomething($options=array()){
   extract($options);
}
//call it
$r=dosomething(array(
   'parameter1'=>5,
   'param2'=>'chickens',
   'sport'=>'Cross Country',
));

this way I can even elect to NOT pass an argument if that fits, and get no warning/notice.
Sam

traq

You do instantiate the object, you're just accessing the result without assigning a reference - so the object (or function return value) is lost afterwards.

Weedpacket

sfullman wrote:
as I'm doing more javascript, I quickly realize that javascript's object oriented (right term?) structure is cool for chaining as in somefunction()[0] or the like. And I see you guys are saying that's available in 5.4, so that I will definitely start using! I have never done OOP in PHP and probably never will, but that [] syntax is definitely nice to use.

This has nothing to do with object orientation; in [font=monospace]somefunction()[0][/font], [font=monospace]somefunction()[/font] is any function call that returns an array (or a string, or an object that implements ArrayAccess) that you're assuming is guaranteed to have an element with a 0 index.

this way I can even elect to NOT pass an argument if that fits, and get no warning/notice.

Uh, you do know that PHP already has facilities for this, right? Optional arguments, and functions for examining the argument list?