PHP: dynamic default value for functions' parameters

Question

I would like to keep options in a Config class, so I don't need to change several (identical) values when changing (e.g.) MySQL database. So far I'm accessing these options like:

Config::$credentials["mysql"]["username"]

now, I would like to set a "dynamic" default value for a function, but PHP won't let me do something like

public function get_single_db_entry($uid, $table=Config::$credentials["mysql"]["table"]) {
    // logic here...
}

What I would like to know: Is there any chance to keep default parameters' values dynamic?

@llamerr I like the array look ;) (but constants wouldn't work here as well, would they?) — Peter
– Peter, Commented Apr 29, 2012 at 14:13
i also tested this as class constant but you can't have class constant as array, so you need something else, like in answer for example codepad.org/GfFvhiOa — llamerr
– llamerr, Commented May 7, 2012 at 9:25

Matzi · Accepted Answer · 2012-04-26 13:17:38Z

3

I think it is not possible this way. But you can render a static default value to it, and in the first line, if the value is unchanged by the caller, you just assign, the dynamic value.

public function get_single_db_entry($uid, $table=0) {
    if $table == 0 
      $table = Config::$credentials["mysql"]["table"]
    // logic here...
}

A bit workaround, but it should work.

answered Apr 26, 2012 at 13:17

Matzi

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Victor Bocharsky · Accepted Answer · 2015-07-09 10:27:09Z

0

You could use my tiny library ValueResolver in this case, for example:

$table = ValueResolver::resolve($table, Config::$credentials["mysql"]["table"]);

and don't forget to use namespace use LapaLabs\ValueResolver\Resolver\ValueResolver;

There are also ability to typecasting, for example if your variable's value should be integer, so use this:

$id = ValueResolver::toInteger('6 apples', 1); // returns 6
$id = ValueResolver::toInteger('There are no apples', 1); // returns 1 (used default value)

Check the docs for more examples

answered Jul 9, 2015 at 10:27

Victor Bocharsky

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