While reading some code, I came across a pleasantly surprising snippet that a coworker had added, and it went something like this:

Calling functions through variables

function display_output()

{

    return 'This is the output text!';

}

$variable = 'display_output';

echo $variable();



Result: $variable() = 'This is the output text!';

With closer inspection, this is a pretty cool feature in PHP. It allows you to dynamically call a function by treating a variable like a function. When parentheses are after the variable name, PHP calls the function whose name equals the variable's value. Ex: if $foo = 'bar', then doing $foo() will try calling a function named bar(). Sure, the same result can be achieved using IF loops, but in PHP, it's always good to at least know of the alternatives.

Variable variables

$charlie = 'delta';

$delta = 'oscar';

echo $$charlie;



Result: $$charlie = 'oscar';

My coworker, Oscar, also informed me about "variable variables". These buggers have that extra dollar sign. In the previous example, PHP looks at the value of $charlie, which is 'delta'. It then returns the value of $delta, which is 'oscar'.

Creating variables dynamically

$when = 'future';

$variable_past = 'Welcome to the past';

${'variable_' . $when} = 'Welcome to the ' . $when;



Result: $variable_future is created, and $variable_future = 'Welcome to the future'

This is helpful for when you need to create numerous variables on the fly, such as within a FOR loop. However, it may end up making more sense to create an associative array, depending on how much data you need stored. Ex: $container_array['dynamic_name'] = 'some_value'; Again, this all depends on your given situation.