Error Stack Implementation
Error code for an attempt to instantiate a non-class as a PEAR_ErrorStack in the singleton method.
Error code for an attempt to pass an object into PEAR_ErrorStack::getMessage()
If this is returned, then the error is completely ignored.
If this is returned, then the error will only be logged, but not pushed onto the error stack.
If this is returned, then the error will only be pushed onto the stack, and not logged.
If this is returned, then the error will be both pushed onto the stack and logged.
Pop an error off of the error stack
Remove a callback from the error callback stack
Add an error to the stack
Set an error Callback If set to a valid callback, this will be called every time an error is pushed onto the stack. The return value will be used to determine whether to allow an error to be pushed or logged.