A system reference that lets a subclass call
the PUBLIC and PROTECTED instance methods of its super class in
the inherited class hierarchy. If the specified method definition
is not found in the subclass's immediate super class, ABL repeatedly
looks to the next super class in the inherited class hierarchy until
it finds the definition.
Syntax
SUPER:method-name ( [ parameter [ , parameter ] ... ] ) [ NO-ERROR ]
|
-
method-name
-
Specifies the name of an instance method defined in a super class.
The method definition cannot be abstract or ABL raises a compiler error.
- ( [
parameter
[ , parameter
]
...
] )
-
Specifies zero or more parameters passed to a PROTECTED or PUBLIC
method that is defined for the super class. You must provide the parameters
identified by the specified method, matched with respect to number,
data type, and mode. To invoke a method that is overloaded in the
class, you must specify sufficient information for each parameter in
order to disambiguate it from all the other methods that it overloads.
Otherwise, ABL raises an error identifying the ambiguity.
For
information on the parameter passing syntax and disambiguating overloaded
methods, see the Parameter passing syntax reference entry.
- NO-ERROR
-
Suppresses ABL errors or error messages that would otherwise occur
and diverts them to the ERROR-STATUS system handle. If an error occurs, the action of the statement
is not done and execution continues with the next statement. If
the statement fails, any persistent side-effects of the statement
are backed out. If the statement includes an expression that contains
other executable elements, like methods, the work performed by these
elements may or may not be done, depending on the order the AVM
resolves the expression elements and the occurrence of the error.
To
check for errors after a statement that uses the NO-ERROR option:
- Check the ERROR-STATUS:ERROR attribute to see if the AVM raised
the ERROR condition.
- Check if the ERROR-STATUS:NUM-MESSAGES attribute is greater than
zero to see if the AVM generated error messages. ABL handle methods
used in a block without a CATCH end block treat errors as
warnings and do not raise ERROR, do not set the ERROR-STATUS:ERROR
attribute, but do add messages to the ERROR-STATUS system handle.
Therefore, this test is the better test for code using handle methods
without CATCH end blocks. ABL handle methods used in a block with a
CATCH end block raise ERROR and add messages to the error object
generated by the AVM. In this case, the AVM does not update the
ERROR-STATUS system handle.
- Use ERROR-STATUS:GET-MESSAGE( message-num )
to retrieve a particular message, where message-num is
1 for the first message.
If the statement does not include
the NO-ERROR option, you can use a CATCH end block to handle errors
raised by the statement.
Some other important usage notes
on the NO-ERROR option:
- NO-ERROR does not suppress errors
that raise the STOP or QUIT condition.
- A CATCH statement, which introduces a CATCH end block, is analogous
to a NO-ERROR option in that it also suppresses errors, but it does so
for an entire block of code. It is different in that the error messages
are contained in a class-based error object (generated by the AVM
or explicitly thrown), as opposed to the ERROR-STATUS system handle.
Also, if errors raised in the block are not handled by a compatible
CATCH block, ON ERROR phrase, or UNDO statement, then the error
is not suppressed, but handled with the default error processing
for that block type.
- When a statement contains the NO-ERROR option and resides in
a block with a CATCH end block, the NO-ERROR option takes precedence over
the CATCH block. That is, an error raised on the statement with
the NO-ERROR option will not be handled by a compatible CATCH end block.
The error is redirected to the ERROR-STATUS system handle as normal.
- If an error object is thrown to a statement that includes the NO-ERROR
option, then the information and messages in the error object will
be used to set the ERROR-STATUS system handle. This interoperability
feature is important for those integrating code that uses the traditional
NO-ERROR technique with the newer, structured error handling that
features error objects and CATCH end blocks.
Notes
- You
typically use the SUPER system reference within a method of a class
defined somewhere in the hierarchy to invoke a method defined in
a super class that was overridden in a subclass. For more information about
using the SUPER system reference, see OpenEdge Development:
Object-oriented Programming.
- You cannot use the SUPER system reference to call a static method.
