Author: leo
Date: Fri Apr 7 09:59:18 2006
New Revision: 12135
Modified:
trunk/docs/pdds/clip/pddXX_exceptions.pod
Log:
fix exception example
Modified: trunk/docs/pdds/clip/pddXX_exceptions.pod
==============================================================================
--- trunk/docs/pdds/clip/pddXX_exceptions.pod (original)
+++ trunk/docs/pdds/clip/pddXX_exceptions.pod Fri Apr 7 09:59:18 2006
@@ -247,30 +247,23 @@
Exception handlers are derived from continuations. They are ordinary
subroutines that follow the Parrot calling conventions, but are never
explicitly called from within user code. User code pushes an exception
-handler onto the control stack with the C<set_eh> opcode. The system
+handler onto the control stack with the C<push_eh> opcode. The system
calls the installed exception handler only when an exception is thrown.
- newsub P20, .Exception_Handler, _handler
- set_eh P20 # push handler on control stack
- null P10 # set register to null
+ push_eh _handler # push handler on control stack
find_global P10, "none" # may throw exception
clear_eh # pop the handler off the stack
...
_handler: # if not, execution continues here
- is_null P10, not_found # test P10
+ get_params '(0,0)', P0, S0 # handler is called with (exception, message)
...
-This example creates a new exception handler subroutine with the
-C<newsub> opcode and installs it on the control stack with the
-C<set_eh> opcode. It sets the C<P10> register to a null value (so it
-can be checked later) and attempts to retrieve the global variable
-named C<none>. If the global variable is found, the next statement
+If the global variable is found, the next statement
(C<clear_eh>) pops the exception handler off the control stack and
normal execution continues. If the C<find_global> call doesn't find
-C<none> it throws an exception by pushing an exception object onto the
-control stack. When Parrot sees that it has an exception, it pops it
-off the control stack and calls the exception handler C<_handler>.
+C<none> it throws an exception by passing an exception object to the
+exception handler.
The first exception handler in the control stack sees every exception
thrown. The handler has to examine the exception object and decide
