Store function result to variable for later use in PHP?

Question

Considering the time I've been using PHP I feel shame for asking this, but it seems I'm way too tired to solve it by myself at this moment.

I have a php variable function that gets an CSV file and stores the data into an array.

$csvdata = function(){
    // Get CSV data to array
    return $array;
}

This array is used by other functions in different situations.

The thing is that I though this functions will run just once, but I just noticed it runs every time I use the var $csvdata.

What I want is to create a self evoked function that runs only once and store the data into an array that I can use as many times as needed without PHP re-doing the process of getting the csv and storing the data every time I use $csvdata.

Its really weird because I feel like if my brain is playing a joke on me... (Brain: "It's obvious... I know the answer but I wont tell you")

Sorry pals

trincot · Accepted Answer · 2016-07-16 10:14:54Z

6

You can call newly created functions on the fly with call_user_func:

$csvdata = call_user_func(function(){
    // Get CSV data to array
    return $array;
});

Then just reference $csvdata as a variable (without parenthesis).

Explanation

The documentation calls the argument to call_user_func a callback, and that is what it is: you pass a function reference to it, and it is the implementation of call_user_func that calls your function for you ("calling you back"). The function reference can be an inline, anonymous function (like above).

But it can also be a variable representing a function:

$func = function(){
    // Get CSV data to array
    return $array;
};
$csvdata = call_user_func($func);

Or, it can be a string, which holds the name of the function:

function myFunc(){
    // Get CSV data to array
    return $array;
};
$csvdata = call_user_func('myFunc');

All of these do the same: your function gets called. You can even tell call_user_func which arguments to pass to your function:

function myFunc($arg){
    echo $arg;
    // Get CSV data to array
    return $array;
};
$csvdata = call_user_func('myFunc', 'hello');

The above will echo 'hello'.

I provide these variants just for information, as your interest is in the inline function argument. Also then you can pass arguments:

$csvdata = call_user_func(function($arg1, $arg2){
    echo $arg1 . "," . $arg2;
    // Get CSV data to array
    return $array;
}, 'hello', 'there');

edited Jul 16, 2016 at 10:14

answered Jul 16, 2016 at 9:31

trincot

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4 Comments

Luis Rivera Over a year ago

Thanks @trincot It works! Could you provide some explanation in your answer of why using call_user_func() did the trick? I was reading the documentation but it is very poor to give me an idea of why now it's running just once. Just for future reference... Thanks again!

Arun Kumaresh Over a year ago

call_user_func is used for calling the function whose name you don't know if you have a funcion with name you can call it by just calling its name

Luis Rivera Over a year ago

@ArunKumaresh I would be lying if I say that I understand your comment LOL

Arun Kumaresh Over a year ago

see my answer then you can understand the differnece

Arun Kumaresh · Accepted Answer · 2016-07-16 09:57:56Z

0

you can give a name to the function and make a call like this

  function csv(){
        // Get CSV data to array
        return $array;
    }

    $csvdata=csv();

answered Jul 16, 2016 at 9:57

Arun Kumaresh

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4 Comments

Luis Rivera Over a year ago

This wont work. Is exactly the same I want to avoid. This way every time you call $csvdata php will run csv(). In my case, this means it will load the csv file and work on it every time I use this var.

DarkBee Over a year ago

Not true, the function csv will only be called once as $csvdata will hold an array and not a closure like in your example

Arun Kumaresh Over a year ago

@luis see the difference between your code and this answer

Luis Rivera Over a year ago

Arun and @DarkBee you guys are correct. This is why resting is an important part of life. I though my version was somehow a shorthanded version of yours, but now I see there's a difference. I'm going to research a bit about closure to get a better understanding of when it should be used. Now I think this is the correct answer given the fact that I was wrongly using 'closure'. Thanks pals!

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