How do you decide that a function must return a value? Give one such example also.
Answers
Answer:
12.4 Functions that Return Values
A return is a value that a function returns to the calling script or function when it completes its task. A return value can be any one of the four variable types: handle, integer, object, or string. The type of value your function returns depends largely on the task it performs.
You use the Function Returns edit combo box in the General page of the New Script dialog to tell JAWS the type of value the function returns. You also type the description of the return in the Return description edit box. Adding a description for the return, helps you and anyone else using your function to determine exactly what the value should be used for within the calling script or function.
When you create a new function that returns a string value, the Script Manager places the following function beginning line into your script file:
String Function MyFunction ()
The "string" key word that precedes the "function" key word tells you that the MyFunction function returns a string value to the calling script or user-defined function.
The Return Statement
You use the return statement to send a value back to the calling script or user-defined function. This key word tells JAWS to return the specified value to the calling script or function. You can return the value as a literal value or within a variable. The syntax of a return statement that sends a string value stored in a variable called sText back to the calling script or user-defined function follows:
Return sText
A return statement that returns a string of text, "This is a string", as a literal follows:
Return "this is a string"
When a function returns a value to the calling script or user-defined function, you must store that value in either a local or global variable. You can then use that variable to make decisions on what the calling script or user-defined function should do next. An example of storing a string value returned by a function called MyFunction in a local variable follows:
Example 1: Assigning the Output of a Function to a Variable
Script MyScript ()
Var
String sText
Let sText = MyFunction (); store the return value of MyFunction in sText
If sText != "" Then; the function actually returned a value other than null or nothing
SayFormattedMessage (OT_MESSAGE, sText)
EndIf
EndScript
You can also use the return value of one function as the parameter for another. Using the previous example, the return value from MyFunction could be passed directly to the SayFormattedMessage function without storing it in a local variable first. The only disadvantage to this approach is that the MyFunction function may not retrieve any text. Therefore, the SayFormattedMessage function won't cause JAWS to speak anything. The example reworked to use the return value of MyFunction as the parameter for SayFormattedMessage follows:
Example 2: Using a Function as a Parameter For Another Function
Script MyScript ()
SayFormattedMessage (OT_MESSAGE, MyFunction()); use the return value from MyFunction as the message text for SayFormattedMessage
EndScript
Another example of a user-defined function that returns a value follows:
string function VerbosityLevelToggle(int iRetCurVal)
Var
int Verbosity
if not iRetCurVal then
; update it
VerbosityLevel ()
endIf
let Verbosity = GetVerbosity ()
if Verbosity == 0 then
return cmsg12_L; Beginner
elif Verbosity == 1 then
return cmsg13_L; Intermediate
elif Verbosity == 2 then
return cmsg14_L; Advanced
endIf
EndFunction
You can find the function shown above in the default script file. JAWS performs this function each time you press SPACEBAR on the "User Verbosity" entry in the Adjust JAWS Options dialog. The function begins by determining the value of the iRetCurVal parameter. If the value of the parameter is 0 or false, then JAWS performs the VerbosityLevel function to change the verbosity level from its current value to the next value. For example, if you are using the beginner verbosity level, the VerbosityLevel function changes your verbosity level to intermediate. Next, the GetVerbosity function retrieves the verbosity setting now being used and stores it in the Verbosity local variable. The If statement then determines the value stored in the Verbosity variable and returns the appropriate string of text to indicate the new verbosity level. The actual text is stored in the Common.jsm JAWS message file found in your JAWS settings folder.