RETURN statement

Leaves the local or remote procedure or user-defined function block, trigger block, database trigger block, the method block of a class, the class constructor block, or the property accessor block, and returns to the calling procedure, user-defined function, method, constructor, or property accessor. If there is no caller, RETURN returns to the Procedure Editor or other ADE or Progress Developer Studio for OpenEdge tool that invoked the procedure, user-defined function, trigger block, database trigger, class-based method, constructor, or property accessor.

For more information on remote procedures, see OpenEdge Application Server: Developing AppServer Applications.

Syntax

RETURN 
    [return-value|
       ERROR [return-value |error-object-expression]|
       NO-APPLY ]

return-value

The value that RETURN returns to the caller, with or without the ERROR condition:

Without the ERROR condition — In a procedure or trigger block, the optional return-value must be a CHARACTER expression. If you do not specify return-value in a procedure or trigger block, return-value is returned as the empty string (""). In a VOID method, you cannot set a return-value. In a user-defined function or in a method of a class that returns a value (non-VOID), return-value must be specified and must be an expression whose data type matches the return type of the function or method; data type matching between the expression and return type follows the data type widening rules for an expression passed to an OUTPUT parameter (see the Parameter passing syntax entry for more information).
With the ERROR condition — In a method of a class (VOID or non-VOID), a constructor, a property accessor, a user-defined function, a procedure, or a database trigger block, the optional return-value must be a CHARACTER expression. If you do not specify either return-value or error-object-expression (see the ERROR option), return-value is returned as the empty string ("").

For more information on how the caller can access return-value in each case, see the ERROR option.

ERROR

Causes an ERROR condition in the calling block. This can cause the ERROR condition to be raised for the following statements in the caller:

The RUN statement for a procedure
Any statement that invokes a user-defined function
Any statement that invokes a method of a class
Any statement that invokes the NEW function (classes) to instantiate a class (invoking the specified constructor and all other constructors for the class hierarchy)
Any statement that accesses a property defined with a property accessor

You can use the ERROR option in a procedure, database trigger block, class-based method, constructor, property accessor method, or user-defined function. However, you cannot use the ERROR option in a user-interface trigger block to raise ERROR outside of the trigger block. Any values that are set for OUTPUT or INPUT-OUTPUT parameters before the RETURN ERROR executes are not returned to the caller.

If return-value is specified, the ABL Virtual Machine (AVM) automatically generates a Progress.Lang.AppError that the caller can obtain using a CATCH statement and obtain return-value from the ReturnValue property of the AppError. If no return-value or error-object-expression is specified, the AVM also generates an AppError with its ReturnValue property set to the empty string (""). The following table shows how to access return-value in the caller in various cases:

In this case . . .	How to retrieve the return value in the caller . . .
The `return-value` is specified without the ERROR option in a procedure or trigger block.	Access the RETURN-VALUE function.
The `return-value` is specified for a non-VOID method or user-defined function without the ERROR option.	In this case, the caller accesses the method or function return value by referencing the function or method call in an expression, similar to referencing a variable.
The `return-value` is specified with the ERROR option.	Access the RETURN-VALUE function, or CATCH the `Progress.Lang.AppError` object automatically created by the AVM and check the `ReturnValue` property of the `AppError` object. Note: User-defined functions have different behavior since they must return the data type specified in the definition. See the FUNCTION statement for more information.
The `error-object-expression` is specified	If `error-object-expression` is a `Progress.Lang.AppError`, CATCH the specified error object and access its `ReturnValue` property, or access the RETURN-VALUE function.

error-object-expression

An expression that resolves to a specific error object. It must be an object derived from Progress.Lang.ProError (you can only THROW error objects) or an object of a class that implements Progress.Lang.Error. It is a compile-time error to THROW an object that is not derived from Progress.Lang.ProError or Progress.Lang.Error. Note that the only error object that you can instantiate directly is a Progress.Lang.AppError object or a subclass.

Note: RETURN ERROR error-object-expression immediately returns to the caller before throwing the error object. Unlike a direct THROW, it ignores any CATCH blocks or ON ERROR directives in effect at the time of the RETURN.

NO-APPLY

Suppresses the default behavior for the current user-interface event. You thus can use the NO-APPLY option in a user-interface trigger block to suppress that behavior. For example, the default behavior for a character code key press in a fill-in field is to echo the character in the field. If you execute RETURN NO-APPLY in a trigger, this behavior is not performed. Also, NO-APPLY returns without setting a return-value or error object.

If you do not specify any options for the RETURN statement in a procedure or trigger block, return-value is returned as the empty string (""). In a VOID method, you cannot specify any options except for the ERROR options, and RETURN without ERROR options returns without setting a return-value or error object.

Examples

The r-fact.p procedure is called recursively because (n factorial) is n * ((n - 1) factorial). The r-fact.p procedure first checks that the input value is valid. If the value is invalid, it returns a message to the caller. Note that r-return.p checks the ReturnValue property immediately after running r-fact.p. If a message is returned, r-return.p displays that message.

The procedure r-return.p accepts an integer as input and then runs r-fact.p to calculate the factorial of that integer. The factorial of a number is the result of multiplying together all of the integers less than or equal to that number (for example: 3 factorial is 3 * 2 * 1 = 6). The r-fact.p procedure is called recursively because n factorial is n * (n -1) factorial.

r-return.p

/* ***************************  Definitions  ************************** */
DEFINE VARIABLE ix    AS INTEGER NO-UNDO.
DEFINE VARIABLE n     AS INTEGER NO-UNDO LABEL "N" FORMAT "->9".
DEFINE VARIABLE nfact AS INTEGER NO-UNDO LABEL "N Factorial" 
  FORMAT ">,>>>,>>>,>>9".

/* ***************************  Main Block  *************************** */
REPEAT:
  SET n SPACE(5).
  ASSIGN nfact = n.
  RUN r-fact.p (INPUT-OUTPUT nfact).
  DISPLAY nfact.

  CATCH mae AS Progress.Lang.AppError:
    REPEAT ix = 1 TO mae:NumMessages:
      MESSAGE "Error Number: " mae:GetMessageNum(ix) SKIP
        "Message: " mae:GetMessage(ix) SKIP
        "NumMessage: " ix VIEW-AS alert-box.
    END. 
    MESSAGE "Here is the ReturnValue " mae:ReturnValue VIEW-AS ALERT-BOX. 
  END CATCH.
END. /* REPEAT */

r-fact.p

/* ***************************  Definitions  ************************** */
DEFINE INPUT-OUTPUT PARAMETER nfact AS INTEGER NO-UNDO.

DEFINE VARIABLE ix  AS INTEGER NO-UNDO.
DEFINE VARIABLE mye AS Progress.Lang.AppError NO-UNDO.

/* ***************************  Main Block  *************************** */
IF nfact < 0 THEN DO:
  mye = NEW Progress.Lang.AppError("The value is negative", 200). 
  mye:ReturnValue = "User inputs out of range".
  RETURN ERROR mye.
END.

IF nfact > 12 THEN DO:
  mye = NEW Progress.Lang.AppError
    ("Factorial value won't fit in an integer.", 201).
  mye:ReturnValue = "Calculated value out of range".
  RETURN ERROR mye.
END.

ASSIGN
  ix    = nfact
  nfact = nfact - 1.

IF nfact <= 1 THEN DO:
  ASSIGN nfact = ix.
  RETURN.
END.

RUN r-fact.p (INPUT-OUTPUT nfact).
ASSIGN nfact = nfact * i.
RETURN.

Note that this is not the most efficient way to calculate factorials, but in other applications, such as bill of material explosions, recursive procedures are very effective.

Notes

The RETURN-VALUE function provides the value returned by the most recently executed RETURN or THROW with options that set or clear a return-value.
If a procedure executing the RETURN statement is called asynchronously, the client can access the return-value and ERROR condition in the associated event procedure. For more information on event procedures, see OpenEdge Application Server: Developing AppServer Applications.
Class-based error objects can be thrown from an AppServer and handled by a CATCH block on an ABL client. To be throwable from an AppServer to an ABL client, user-defined error classes must be defined on both the server and client sides, and the classes must be defined as SERIALIZABLE. For the full list of restrictions on class-based objects that are passed between AppServer and client, see the Parameter passing syntax entry. For more information on error handling in general, see OpenEdge Development: Error Handling.
Class-based error objects can also be thrown from an AppServer to a client for an asynchronous request. One way to throw a class-based error object from an AppServer to a client for an asynchronous request is by doing RETURN ERROR. In this case, the error object is returned to the client via the ERROR-OBJECT attribute of the Asynchronous request object handle.

RETURN statement

Syntax

Examples

Notes

See also