Code Review Asked by Ngoy Lufo on December 12, 2020
Given the following generic memoize utility for pure functions with type hints:
function memoize(callable $fn, callable $serialize = null): callable {
$serialize = $serialize ? $serialize : 'serialize';
return function(...$args) use ($fn, $serialize) {
static $cache = [];
$k = $serialize($args);
return isset($cache[$k]) ? $cache[$k] : ($cache[$k] = $fn(...$args));
};
}
Is the callable type hint here preferred as opposed to closure? I’m also not sure if I’m being too pedantic with the type hints and whether my use of static here is recommended?
I’d appreciate any feedback on the code above.
To address your first question:
Is the callable type hint here preferred as opposed to closure?
There is a very similar question on StackOverflow: PHP: Type hinting - Difference between Closure
and Callable
. It has three answers.
The first line of the answer by Xorifelse explains:
The main difference between them is that a
closure
is a class andcallable
a type.
And the last line of the accepted answer by Rizier123 has this suggestion:
So if you only want to type hint anonymous function use:
Closure
and if you want also to allow normal functions usecallable
as type hint.
And now, for something completely different general code review comments:
The name $k
is a little too brief... $key
isn't very long and describes what the variable is.
Correct me if I am mistaken but as long as PHP 5.3+ is used then this line:
$serialize = $serialize ? $serialize : 'serialize';
could be shortened using the fact that:
The expression
(expr1) ? (expr2) : (expr3)
evaluates to expr2 if expr1 evaluates to TRUE, and expr3 if expr1 evaluates to FALSE.
Since PHP 5.3, it is possible to leave out the middle part of the ternary operator. Expressionexpr1 ?: expr3
returns expr1 if expr1 evaluates toTRUE
, and expr3 otherwise.1
to the following:
$serialize = $serialize ?: 'serialize';
If PHP 7+ is used (which hopefully is the case, since at the time of writing, 7.2+ are actively maintained2) then the null coalescing operator i.e. ??
could also be used to simplify cases where a fallback should be used if a non-null value does not exist - e.g. :
return isset($cache[$k]) ? $cache[$k] : ($cache[$k] = $fn(...$args));
Can become:
return $cache[$k] ?? ($cache[$k] = $fn(...$args));
Correct answer by Sᴀᴍ Onᴇᴌᴀ on December 12, 2020
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