How can I catch a "catchable fatal error" on PHP type hinting?
PhpFatal ErrorType HintingPhp Problem Overview
I am trying to implement Type Hinting of PHP5 on one of my class,
class ClassA {
public function method_a (ClassB $b)
{}
}
class ClassB {}
class ClassWrong{}
Correct usage:
$a = new ClassA;
$a->method_a(new ClassB);
producing error:
$a = new ClassA;
$a->method_a(new ClassWrong);
>Catchable fatal error: Argument 1 passed to ClassA::method_a() must be an instance of ClassB, instance of ClassWrong given...
Is it possible to catch that error(since it says "catchable")? and if yes, how?
Php Solutions
Solution 1 - Php
Update: This is not a catchable fatal error anymore in php 7. Instead an "exception" is thrown. An "exception" (in scare quotes) that is not derived from Exception but Error; it's still a Throwable and can be handled with a normal try-catch block. see https://wiki.php.net/rfc/throwable-interface
E.g.
<?php
class ClassA {
public function method_a (ClassB $b) { echo 'method_a: ', get_class($b), PHP_EOL; }
}
class ClassWrong{}
class ClassB{}
class ClassC extends ClassB {}
foreach( array('ClassA', 'ClassWrong', 'ClassB', 'ClassC') as $cn ) {
try{
$a = new ClassA;
$a->method_a(new $cn);
}
catch(Error $err) {
echo "catched: ", $err->getMessage(), PHP_EOL;
}
}
echo 'done.';
prints
catched: Argument 1 passed to ClassA::method_a() must be an instance of ClassB, instance of ClassA given, called in [...]
catched: Argument 1 passed to ClassA::method_a() must be an instance of ClassB, instance of ClassWrong given, called in [...]
method_a: ClassB
method_a: ClassC
done.
Old answer for pre-php7 versions:
<http://docs.php.net/errorfunc.constants> says:
E_RECOVERABLE_ERROR ( integer )
Catchable fatal error. It indicates that a probably dangerous error occured, but did not leave the Engine in an unstable state. If the error is not caught by a user defined handle (see also http://docs.php.net/manual/en/function.set-error-handler.php">set_error_handler()</a>;), the application aborts as it was an E_ERROR.
see also: <http://derickrethans.nl/erecoverableerror.html>
e.g.
function myErrorHandler($errno, $errstr, $errfile, $errline) {
if ( E_RECOVERABLE_ERROR===$errno ) {
echo "'catched' catchable fatal error\n";
return true;
}
return false;
}
set_error_handler('myErrorHandler');
class ClassA {
public function method_a (ClassB $b) {}
}
class ClassWrong{}
$a = new ClassA;
$a->method_a(new ClassWrong);
echo 'done.';
prints
'catched' catchable fatal error
done.
edit: But you can "make" it an exception you can handle with a try-catch block
function myErrorHandler($errno, $errstr, $errfile, $errline) {
if ( E_RECOVERABLE_ERROR===$errno ) {
echo "'catched' catchable fatal error\n";
throw new ErrorException($errstr, $errno, 0, $errfile, $errline);
// return true;
}
return false;
}
set_error_handler('myErrorHandler');
class ClassA {
public function method_a (ClassB $b) {}
}
class ClassWrong{}
try{
$a = new ClassA;
$a->method_a(new ClassWrong);
}
catch(Exception $ex) {
echo "catched\n";
}
echo 'done.';