Variable functions and variable names in PHP

Question

In PHP, say you have code like this:

$infrastructure = mt_rand(0,100); if ($infrastructure < $min_infrastructure) $infrastructure = $min_infrastructure; //do some other stuff with $infrastructure $country->set_infrastructure($infrastructure); $education = mt_rand(0,100); if ($education < $min_education) $education = $min_education; //do some other stuff with $education $country->set_education($education); $healthcare = mt_rand(0,100); if ($healthcare < $min_healthcare) $healthcare = $min_healthcare; //do some other stuff with $healthcare $country->set_healthcare($healthcare); 

Is there a way to combine these similar sets of instructions into a function that can be called as:

 change_stats("infrastructure"); change_stats("education"); change_stats("healthcare"); 

Basically, can variables be used in PHP for other variable names and function names?

Thanks in advance.

Answer 1

You can use what PHP calls "variable variables" for this. I hope your example is contrived, because it looks a little strange, but assuming the variables and objects are global, you can write the name_pet () function as follows:

 function name_pet($type, $name) { $class='the_'.$type; $var=$type.'_name'; $GLOBALS[$class]->setName($name); $GLOBALS[$var]=$name; } 

EDIT : This answer refers to an earlier version of the question.

Answer 2

I'm not sure about this function, but you can do something like this using __set

 $data; function __set($key, $val) { $this->data["$key"] = $val; } 

And yes, you can use variables dynamically

 $foo = "bar"; $dynamic = "foo"; echo $$dynamic; //would output bar echo $dynamic; //would output foo 

Answer 3

Yes, you can, look here for a discussion and here for a tutorial.

Answer 4

To answer your question: Yes, you can use variables as variable names using the syntax $ {$ varname}.

However, this does not seem to be the right solution for what you are trying to do here, since setting $ _ _ {$ petname} variables requires them to be in the scope of the name_pet function.

Could you tell us more about what you are trying to do?

Some suggestions: Let the pet class (or something else that the cat, dog and fish) return the name to be set, so you can do $ fish_name = $ the_fish-> setName ("Goldie");

Or even better, do not use $ fish_name at all, as this information is now stored in the object ... you can simply call $ the_fish-> getName (); where you will use $ the_fish.

Hope this helps?

Answer 5

This is an interesting question because it is a common template and it is especially important to monitor refactoring.

In a purely functional form, you can use the following code:

 function rand_or_min( $value, $key, $country ) { $rand = mt_rand(0,100); if ($rand < $value ) { $rand = $value; } // do something call_user_func( array( $country, 'set_' . $value ), array( $rand ) ); } $arr = array('infrastructure' => 5,'education' => 3,'healthcare' => 80); array_walk( $arr, 'rand_or_min', $country ); 

Although this works well, I strongly recommend that you use a more object-oriented path. Whenever you see a pattern like the one above, you should think about classes and subclasses. What for? Because there is duplicate behavior and a similar state (variables).

In a more OOP method, this can be implemented as follows:

 class SomeBasicBehavior { function __construct( $min = 0 ) { $rand = mt_rand(0,100); if( $rand < $min ) { $rand = $min }; return $rand; } } class Infrastructure extends SomeBasicBehavior { } class Education extends SomeBasicBehavior { } class Healthcare extends SomeBasicBehavior { } $country->set_infrastructure( new Infrastructure() ); $country->set_education( new Education() }; $country->set_healthcare( new Healthcare() }; 

It is not only more readable, but also much more extensible and easily verifiable. Your “do something” can be easily implemented as member functions in each class, and their behavior can be split as needed (using the SomeBasicBehavior class) or encapsulated as needed.