oop - PHP OO - How should I handle soft errors in multiple classes? -

i apologise if has been answered somewhere, haven't managed find answer far - maybe i'm searching wrong thing!

i trying figure out how handle errors in oo php system, used generate web pages. example explain mean.

imagine have content class, form class , formobject class, hold information on page content, web forms , form fields. classes can run multiple mysql queries via db class. users can create new content or forms in back-end. when this, use classes create , store data in database.

i have system class, used generate web pages. system class checks should displayed on front-end, builds appropriate content , form objects, generates html , outputs screen.

i have checks serious errors, stop code going further. however, problem want feed "soft errors" front-end. example, maybe system class builds form object, in-turn builds fields using formobject class. formobject class queries database field name, field name not found. db class returns error. want able feed message front-end says field name has not been found.

what best way "soft error" message system class, can outputted front-end? realise simple in particular example, more classes added and, crucially, more levels added, problem becomes bit bigger.

one way thought of doing have error class. system create error object , pass on each content , form object created. form class pass same error object formitem class. whenever error found, logged via method in error class. system can access original error object , output errors. however, system grows, more classes added, , more objects created, quite confusing. there better way?

you might want use either

1. something global classes can access (e.g. global variable or singleton), or
2. something passed in instantiations of classses producing call 'soft errors'

to collect such errors. want use whatever collected , add output in system class somehow.

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to more specific...

this example solution using global:

global $softerrormessages = array();  class {   function samplefunctiona()   {     // [...]     // code setting $result valid value     // or false if error occured      if($result === false) // check validity     {       global $softerrormessages;       $softerrormessages[] = "the sample function caused soft error";       return;      }      // [...]     // code requiring valid $result   } } 

if use such global, can access system class , put contents right places of output.

however, if perform unit tests, might not want use globals or global-like solutions (like singletons). here example 'error collection' approach:

class errorcollector {   private $errors = array();    function adderror($error)   {     $this->errors[] = $error;   }    function geterrors()   {     return $this->errors;   } }  class {   private $errorcollector;    function __construct(/* additional parameters */, errorcollector $errorcollector)   {     // [...]     // additional instantiation stuff      $this->errorcollector = $errorcollector;   }    function samplefunctiona()   {     // [...]     // code setting $result valid value     // or false if error occured      if($result === false) // check validity     {       $this->errorcollector->adderror("the sample function caused soft error");       return;      }      // [...]     // code requiring valid $result   }  } 

you instantiate errorcollector once , pass other class instantiations. let objects perform duties (and possibly add soft errors errorcollector). once they're done, system class error messages , - again - place them @ right place of output.