CODEWITHSUNDEEP
phparraysoptimizationmicro-optimization
Sebastian Tkaczyk
Sebastian Tkaczyk

Reputation: 372

Most optimized way to create associative array

What is the best (fastest, most readable, etc.) way to create associative array?

Last time I saw that my co-worker, create small assoc array by:

$array['is_enabled'] = false;

In code review i pass my opinion that more readable form is:

$array = [
    'is_enabled' => false
];

But "readable" is subjective thing, so it's not the best argument.

Upvotes: 0

Views: 192

Answers (1)

Sebastian Tkaczyk
Sebastian Tkaczyk

Reputation: 372

The first approach 3v4l link:

$subscription['is_enabled'] = false;

You can see in link that's generated 3 operations

number of ops:  3
compiled vars:  !0 = $subscription
line     #* E I O op                           fetch          ext  return  operands
-------------------------------------------------------------------------------------
   3     0  E >   ASSIGN_DIM                                               !0, 'is_active'
         1        OP_DATA                                                  
         2      > RETURN                                                   1

Avg. memory usage is 25.15 MiB and runs in 0.013s (user time PHP 7.1.x).

The second approach 3v4l link:

$subscription = ['is_active' => false];

Now it's only 2 operations. Assign and return.

number of ops:  2
compiled vars:  !0 = $subscription
line     #* E I O op                           fetch          ext  return  operands
-------------------------------------------------------------------------------------
   3     0  E >   ASSIGN                                                   !0, 
         1      > RETURN                                                   1

Avg. memory usage is 24.40 MiB and runs in 0.010s (user time PHP 7.1.x).

I'm not sure what operation is op_data that is missing in second approach. But still it's one operation less, and in result we gain almost 0,8MiB less memory usage and ~23% faster execution time.

So it's looks like $array= ['key' => false];

It's not only more readable but also quite simpler for parser. With this notation we skip one operation from three, and that's give us additional free memory and time.

Upvotes: 2

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