How to manage exceptions in multiple nested functions?

Question

I am learning how to use Exceptions in PHP. In a subfunction of my code, I want to throw an Exception to stop the main function if an error appears.

I have three functions:

function main_buildt_html(){
    ...
    check_if_parameters_are_ok();
    // if the subfunction_check exception is thrown, don't execute the process below and go to an error page
    ...
}

function check_if_parameters_are_ok(){
    ...
    try{
        ...
        subfunction_check();
        ...
    }catch(Exception $e){

    }
    ...
}

function subfunction_check(){
    ...
    if ($some_error) throw new Exception("Its not ok ! stop the process and redirect the user to an error page");
    ...
}

From my main "main_buildt_html" function, how can I properly detect if an exception has been thrown?

I want to detect the "subfunction" exception from the main function so I can stop the standard process and redirect the user to an error HTML page.

Answer 1

Normally the exception will be throwin up until the highest level in the chain, or when you catch it in any level.

in your case, if you want to catch the exception in check_if_parameters_are_ok() and main_buildt_html() functions, you need to throw the exception up in the check_if_parameters_are_ok() function.

function check_if_parameters_are_ok(){
    ...
    try{
        ...
        subfunction_check();
        ...
    }catch(Exception $e){
     //handle exception. 
     throw $e; // throw the excption again
    }
}

now you need to catch the excption in the main_buildt_html() function.

function main_buildt_html(){
    try {
        check_if_parameters_are_ok();
    } catch (Exception $e) {
        // handle the excption
    }   
}