The Error Listener
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The Error Listener receives notification of all warnings and errors (whether recoverable or not)
generated when compiling the stylesheet, or produced by the XM_XSLT_TRANSFORMER.
XSLT defines some errors as recoverable (and specifies optional recovery options), and others
as non-recoverable. Conditions not defined by XSLT are raised by the library as warnings.
Features
The following features may be of interest to the Eiffel programmer:
- recovery_policy: INTEGER / set_recovery_policy (a_recovery_policy: like recovery_policy)
-
The recovery policy is an instruction to the error routine
as to how to handle recoverable errors. If it evaluates to Recover_silently,
then error is supposed to set recovered to
True, and not issue any message (although it may choose to log the error).
If it evaluates to Recover_with_warnings, then it should additionally
inform the user of the recovered condition, provided recoverable_error_threshold
has not been exceeded (although it is not obliged to honour this threshold).
If, however, it evaluates to Do_not_recover, then it should inform the user
of the error condition, and set recovered to False.
- warning_threshold: INTEGER / set_warning_threshold (a_warning_threshold: like warning_threshold)
-
This threshold is available to request the warning routine
not to issue an informatory message once this number of warning messages have been issued.
- recoverable_error_threshold: INTEGER / set_recoverable_error_threshold (a_recoverable_error_threshold: like recoverable_error_threshold)
-
This threshold is available to request the error routine
not to issue an informatory message once this number of recoverable errors have been seen.
- warning (a_message: STRING; a_locator: XM_XPATH_LOCATOR)
-
This routine is called by the library to warn of problematic conditions which are not defined as errors
by XSLT. It should inform the user (in some unspecified way) about the condition, provided that
warning_threshold has not been exceeded (but there is no obligation to
maintain a count of warning messages, so a pure error listener may well ignore this threshold).
- error (a_message: STRING; a_locator: XM_XPATH_LOCATOR)
-
This routine is called by the library to inform the user (in some unspecified way) about a recoverable
error, provided that recoverable_error_threshold has not been exceeded (but there is no obligation to
maintain a count of error messages, so a pure error listener may well ignore this threshold)
and perhaps recover from the error (both actions depend upon the current setting of recovery_policy).
This routine must set recovered to True
if it recovers from an error, so that the transformer can take the defined recovery action. (This probably means
that a pure error listener will only implement a policy ofDo_not_recover.)
- fatal_error (a_message: STRING; a_locator: XM_XPATH_LOCATOR)
-
This routine is called by the library to inform the user (in some unspecified way) about a
non-recoverable error.
- treat_warnings_as_recoverable_errors
-
This routine may be called by the programmer on an error listener,
to request the warning
routine to behave identically to the error routine.
The default error listener: XM_XSLT_DEFAULT_ERROR_LISTENER
This is the only concrete error listener provided by the library. It maintains error
counts. The recovery policy is passed as an argument to the creation routine, as also is
a UT_ERROR_HANDLER to receive the warning and error messages.