How to set/overwrite variable if expression is true without repeating variable name in PHP

Question

I thought I'd seen this before, but I'm not finding it anywhere.

If I have a variable and want to assign it a new value if a condition is true, but otherwise leave the variable alone, is there a way to do this without repeating the variable/original value?

The "long ways" would be:

if($condition == TRUE) {
     $og_value = "New Value";
}

Or:

$og_value = ($condition == TRUE) ? "New Value" : $og_value;

But I seem to remember there is a trick, either built into assignment operators or using bitwise operators to only set $og_value if $condition is true, otherwise it short circuits and leaves $og_value as it was before the assignment/comparison.

possible duplicate of Shortest way to assign a default value to a variable? — outis
– outis, Commented Apr 1, 2012 at 5:49
Subsumed by What are the different ways of writing “if” conditional statements using PHP?, in particular Tom's answer — outis
– outis, Commented Apr 1, 2012 at 6:03

stewe · Accepted Answer · 2012-04-01 05:35:01Z

1

I think you are looking for:

$condition && $og_value = "New Value";

answered Apr 1, 2012 at 5:35

stewe

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7 Comments

Rafe Kettler Over a year ago

This is correct, but let me just address the OP and say that this is atrocious and he should never use this.

Anthony Over a year ago

@RafeKettler - Atrocious to look at or actually bad practice/anti-pattern?

Anthony Over a year ago

@stewe - Thanks! But that looks like it sets them both (even if it doesn't). Is that what makes it atrocious like Rafe says?

Anthony Over a year ago

@RafeKettler Well, the first thing I noticed is that the order matters, which makes sense, but it took me 5 minutes to figure out why it wasn't working. Second thing is, I still have to repeat the variable name if I just want to set it's value if it's not already set, with the above it would be !$og_value && $og_value = "default"; And that is atrocious even to me.

stewe Over a year ago

@Anthony: An if-statement is the best choice because everything else may lead to confusion about what the program really does (maybe you experienced that ^^). Especially if the code gets bigger, with lots of people working on it, readability becomes more and more important.

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