动态构建和执行函数[PHP]

Question

I have a function defined as:

function foo($params)
{
    echo "Hello ".$params;
}

Then, in another file, I have:

$functionName = "foo";
$functionParams = "World";

include("./path_to_file_where_above_function_exists.php");

$functionName($functionParams);

This outputs, as expected:

Hello World

So far so good, what I want to know is how can I check if the function exists in the other file? For example, if I change:

$functionName = "foo";

to

$functionName = "bla";

The code throws no errors. Any help on how to properly handle errors in this case?

Thank you.

Answer 1

You can check the ability to call a function with help is_callable(). For example:

function foo($params)
{
    echo "Hello ".$params;
}

$functionName = "foo";
$functionParams = "World";
if (!is_callable($functionName)) {
    echo "{$funtionName} is not a function"
}