Quicker $foo ? $foo : 'bar'

Question

A line of code speaks a gazillion words so:

$foo = false;
$bar = $foo ? $foo : 'bar';
/* $bar == 'bar' */

$foo = 'foo';
$bar = $foo ? $foo : 'bar';
/* $bar == 'foo' */

Is there a quicker way of saying "if something isn't false, then don't change it (if $foo isn't false then it stays as whatever it was, else, we'll change it)"?

"Quicker" not in terms of execution speed but in terms of coding I suppose? — Ates Goral, Apr 06 '11 at 14:07
"if something isn't false, then don't change it" Wait, that's not what your code is doing. Your code is always changing something. — R. Martinho Fernandes, Apr 06 '11 at 14:07
I think he means as opposed to something like a `coalesce` statement, where as long as the value is set/non-false/non-null, you keep it, otherwise revert to a default value. — Jimmy Sawczuk, Apr 06 '11 at 14:08
http://stackoverflow.com/questions/1013493/coalesce-function-for-php/1891899#1891899 — Ates Goral, Apr 06 '11 at 14:08
Sorry, to specify: coding speed, not execution speed. Thanks for the quick responses guys! — Jonathon Oates, Apr 06 '11 at 14:15

score 10 · Accepted Answer · answered Apr 06 '11 at 14:07

10

Really: Thats really short! :D However, since 5.3 it gets even shorter

$bar = $foo ?: 'bar';

answered Apr 06 '11 at 14:07

KingCrunch

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It's still `?:` in 5.3 (not `:?`), but you can leave out the middle part now. – Arc Apr 06 '11 at 14:11

score 7 · Answer 2 · answered Apr 06 '11 at 14:32

7

Try to think not only of quicker writing but also of quicker reading.
Eventually you will learn that comfortable reading is way more important than these silly tricks in writing.

answered Apr 06 '11 at 14:32

Your Common Sense

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Agreed. If you want quicker coding, use your IDE's macro function. – Pekka Apr 06 '11 at 17:39

score 2 · Answer 3 · answered Apr 06 '11 at 14:08

2

$foo = false;
$bar = $foo ?: 'bar';

should return 'bar

$foo = true;
$bar = $foo ?: 'bar';

should return true;

AS of 5.3

answered Apr 06 '11 at 14:08

Ian Wood

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score 1 · Answer 4 · answered Apr 06 '11 at 14:06

1

"Quicker" by what metric?

In terms of runtime, this will never be your bottleneck, so don't worry about it.

In terms of legibility, the following is clearly easier to read:

$foo = false; // done elsewhere

$bar = $foo;
if (!$bar) {  // I've assumed from your examples that
              // you meant more than just "not false"
   $bar = 'bar';
}

answered Apr 06 '11 at 14:06

Lightness Races in Orbit

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Go on... put some braces in there. – Joe Apr 06 '11 at 14:07
Not really... he assigns `$foo` to `$bar` only if `$foo` evaluates to `TRUE`, otherwise `'bar'`. However, your example will modify `$foo` as well. – Arc Apr 06 '11 at 14:09
@Archimedix, @Martinho: Read it again. – Lightness Races in Orbit Apr 06 '11 at 14:09
I disagree: If you are familiar with the ternary-operator its more readable, than that. – KingCrunch Apr 06 '11 at 14:09
@KingCrunch: You certainly have the right to disagree. Still, I'm more than familiar with the ternary conditional operator and I still find the above far easier to follow at a glance. – Lightness Races in Orbit Apr 06 '11 at 14:10

score 0 · Answer 5 · answered Apr 06 '11 at 14:10

0

My concern is that you could have a value that casts to false

$age = 0;
$myAge = $age ? $age : 21; //If no age assume drinking age

You wont get that with a direct, type sensitive comparison

if ($age ==== false) { 
  //stuff
}

answered Apr 06 '11 at 14:10

preinheimer

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score 0 · Answer 6 · answered Apr 06 '11 at 22:20

0

Not sure why that's always forgotten, but there is also a Perl-esque syntax:

$foo = $foo   or   $foo = "bar";

Or in your case just:

$foo   or   $foo = "bar";

I'm often using excessive spaces to keep it readable. Most importantly it really does no assignment unless $foo is false.

answered Apr 06 '11 at 22:20

mario

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It is indeed better than the full ternary operator, and it's not just quicker, but shorter too: `$x = expensive_function() ? expensive_function() : 1;` ==> `$x = expensive_function() or $x = 1;` – biziclop Sep 07 '13 at 17:03
@biziclop Maybe you meant `$x = expensive_function() ?: 1`? Because your solution always returns a boolean, which may be not wanted. – KingCrunch Oct 27 '13 at 03:08

Quicker $foo ? $foo : 'bar'

6 Answers6