CODEWITHSUNDEEP
phpfunctionconstants
george
george

Reputation: 462

How to define a PHP function with a parameter accepting a fixed set of values?

How can I define a PHP function with a parameter accepting a fixed set of values similar to filter_var which accepts as argument various values as in caps:

http://php.net/manual/en/filter.filters.validate.php

I am guessing it will be something like:

function f(int $params) { ... }

but the question is how to make my own fixed caps typed associations?

Example to clarify:

Currently I have 2 functions:

function defineDirConstant($constant, $dirname) {
    if (is_dir($dirname) && is_readable($dirname)) {
        define(__NAMESPACE__ . '\\' . $constant, $dirname . DIRECTORY_SEPARATOR);
    } else {
        // some other logic
    }
}

function defineFileConstant($constant, $filename) {
    if (is_file($filename) && is_readable($filename)) {
        define(__NAMESPACE__ . '\\' . $constant, $filename);
    } else {
        // some other logic
    }
}

which I am willing to combine into one:

function defineFilesystemConstant($constant, $filename, int $type) {
    // some logic considering the $type
}

I know in this particular case I can use a Boolean for type but my question is in general: how to make a humanly readable parameter which is able to be typed as text. E.g. the function call would be 

f("ONE", "foo.txt", TYPE_FILE);
f("BAR", "bar", TYPE_DIR);
f("JIM", "jimcarrey", TYPE_SOMETHING_ELSE);

I hope that clarifies.

Upvotes: -1

Views: 705

Answers (2)

laurent
laurent

Reputation: 90776

I think what you are looking for is the define() function - you can use that to create constants like those used by the filter_var function.

In your example, you would create these constants:

define('TYPE_FILE', 1);
define('TYPE_DIR', 2);
define('TYPE_SOMETHING_ELSE', 3);

which you can then use in, for example, f("BAR", "bar", TYPE_DIR);.

Or if you want to avoid global constants, you can scope them using a class:

class FileSystemType {
    const FILE = 1;
    const DIR = 2;
    const SOMETHING_ELSE = 3;
}

Which you can then access using:

f("BAR", "bar", FileSytemType::DIR);

Upvotes: 1

JustOnUnderMillions
JustOnUnderMillions

Reputation: 3795

Look here http://php.net/manual/en/migration56.new-features.php:

function f($req, $opt = null, int ...$params) {
     printf('$req: %s; $opt: %s; number of params: %s'."\n",
       $req, $opt, count($params));
}

This function take $reg and $opt as parameters and the array $params hold all next parameters and convert it to int

So f(1,2,3,4) has $reg=1 $opt=2, $params=[3,4].

Or f(1,2,3,4,'5') has $reg=1 $opt=2, $params=[3,4,5].

Know you can check $params and only use valid parameters [ENUMS].

To define ENUMS you can do:

interface MyEnums {
   const VALUE1 = 1;
   const VALUE2 = 2;
}

echo MyEnums::VALUE1;

So if you combine these 2 technics you have something simlliar to your example.

f(1,2,MyEnums::VALUE1,MyEnums::VALUE2);

Keep the comment from @this.lau_ above in mind.

Upvotes: 1

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