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PHP exceptions and the exception handling in general are both-way interoperable with the CLR exception handling. All the throwable exception types in the CLR have to be derived from the System.Exception class, and thus the base PHP exception classes \Error and \Exception are no different.

The following code samples depict the pseudo-implementation of the base PHP exception classes.

// base PHP exception class - \Error
public class Error : System.Exception, Throwable { ... }
// base PHP exception class - \Exception
public class Exception : System.Exception, Throwable { ... }

The entire exception mechanism between .NET languages and PHP works out of the box.

Catch a PHP Exception in C##

Since all the PHP exception classes and user PHP exception classes are derived from System.Exception, thay can be caught in .NET using standard try/catch/finally blocks.

try { /* invoke PHP code */ }
// handle only the Error exception class (full name is Pchp.Library.Spl.Error)
catch (Error err) { ... }
// handle any exception including a PHP exception
catch (Exception ex) { ... }

Catch a C# Exception in PHP#

When catching standard .NET exceptions in PHP code, keep in mind that they are not inherited from PHP's \Exception, \Throwable or \Error types. In order to catch a standard System.Exception or a derived type, the type must be specified in the catch block as follows:

try { /* call a .NET method that throws */}
// C# exceptions don't implement Throwable, won't catch
catch (\Throwable $t) { ... }
// C# exceptions don't inherit PHP \Exception type, won't catch
catch (\Exception $e) { ... }
// catches everything - C# and PHP exceptions
catch (\System\Exception $se) { ... }

Note to Implementors#

In PHP, exceptions are commonly caught using the \Throwable type (which is not implemented by regular C# exceptions). Additionally, the PHP code might expect that an exception object is of the PHP type \Exception, which doesn't have to be true, and it might expect there are certain properties (like Exeption::$file).

Although not compulsory, in order to achieve full interoperability and to avoid any unexpected behavior of the PHP code, the user exceptions thrown from C# and caught by the PHP code should inherit PHP's \Exception class (full CLR name: Pchp.Library.Spl.Exception implemented in Peachpie.Library.dll).