Conditionally add element inside an array(...)

My system sends a configuration array to a function like t开发者_开发知识库his:

callThatFunction( array(k1 => v1,  k2 => v2, ... kn=vn));

I want to make one of the key value pairs, conditional upon some circumstances.

Can I do this without creating a variable for the array (and this breaking the clean config syntax that someone else had created)?

Like this

callThatFunction (
    array(
        k1 => v1, 
        if($cond( {k2 => v2,} 
        ... 
        kn=vn
    )
);

The above is obviously wrong syntactically, but should express my idea.

You can use the conditional operator cond ? true-expr : false-expr:

$someConfig = array(
    'k1' => 'v1',
    'k2' => $cond ? 'v2a' : 'v2b'
);

The conditional expression $cond ? 'v2a' : 'v2b' will yield 'v2a' if $cond evaluates to true and 'v2b' otherwise. But this works only with the value of a key.

If you only want to add a key based on a condition, you need to use a separate if:

$someConfig = array('k1' => 'v1');
if ($cond) {
    $someConfig['k2'] = 'v2';
}

Edit    You can add keys conditionally without a variable using the array union operator or array_merge:

array('k1' => 'v1') + ($cond ? array('k2' => 'v2') : array())
array_merge(array('k1' => 'v1'), $cond ? array('k2' => 'v2') : array())

Now you need to decide what’s more readable or better to maintain.

Eventually I came up with the following:

callThatFunction( array(k1 => v1, k2 => v2, ... kn=vn) + ($cond ? array(key=>value) : array()) )

Will still appreciate a suggestion for somethings that will express the intention more directly

You can assign all values and filter empty keys from the array at once like this:

$myArray = array_filter([
    'k1' => 'v1',
    'k2' => $cond ? 'v2' : false
]);

This allows you avoid the conditional after the fact and imo it's fairly readable.

Put it after the array declaration:

$someConfig = array(
...
);

if($cond){ $someConfig['k2'] = $v2; }

I think all of these answers so far will leave a stub of some kind in the array when the condition is not met.

I suggest setting the array in full, then use the unset function to remove those you don't want. This will give a clean array with only what you want and is also easy to read.

So...

$shapes = array('one'=>'circle, 'three'=>'triangle, 'four'=>'square', 'five'=>'pentagon')
if($i_like_curves==false){
   unset($shapes['one']);
}

Agree with Paul but use array_splice, to remove elements, instead of unset as unset will also leave stubs (empty elements).