Function - IVR Programming Command | Xtend IVR Tutorial

Function <Function Name> ( Param1, Param2, ... )
<statements>
Return <Value>

Identifies the start of a user-defined function.

Parameters

<Function Name> Name of the function.
Param1, Param2, ... Parameters passed to the function and should be separated by commas.
<statements> One or more executable statements inside the function definition.
<expression> Expression which supports variables or value.

Return Value

Returns the value of an expression, a constant or a variable.

Remarks

Another method of calling a function is:

Function <FunctionName>

Parameters <$Param1><,$Param2>...
<statements>

Return [Expression]

Function can also be abbreviated as ' FUNC ' or ' FN '.
Functions must be defined towards the end of the script, i.e, after they are called from the main function. If they are defined at the beginning of the script, the IVR will straightaway execute them.
Either Param or Parameters keyword can be used.

All variables (including parameters) inside a function are local to that function.

All functions are local to the script file in which they are declared.

If a default label like ONHANGUP, ONSYSTEMERROR is not present inside a plugin script, then it will automatically jump to the parent scripts ONHANGUP / ONSYSTEMERROR.

You can call another .dt or .dtx file just like a plugin and it will follow the precedence order given below.

The precedence of a function call is:

Function in current script.
.dtx file in current directory.
.dt file in current directory.
.exe file in current directory.
.dtx file in plugins directory.
.dt file in plugins directory.
.exe file in plugins directory.

Functions can be called recursively.

You can declare a function in an IVR file and call that function like ivrfile.func().

A "goto" from a function than "return", may cause problems in long time execution. A function definition should end up with a return statement.

If you miss a return in a function, the control will carry on the execution of subsequent statements in the next function declared below that.

An external function can be called with a fully qualified filename like d:\Bank\Accounts($acno,$pin).

Defining a function with reserved function name will blindly be ignored. For example, a FN Mid($param) will not get called.

Example
1. Calling a function within the same script:

The above function AddNum adds up the variables $Num1 and $Num2 and the resulting value $Num3 is returned.

AddNum can be beckoned in the script as:

$Num4 = AddNum ($Num1, $Num2)

* In the later case the returned value is assigned to the variable $Num4.
* By giving values 2, 4 respectively to $Num1 and $Num2, the value of $Num3 or $Num4 would be 6.

If this function is not found in the script file then ivr searches for it in the precedence order as given in the remarks section.

2. Calling another .dt or .dtx file just like a plugin: Content of script file "MathOperation.dt":

Content of file "Addition.dt"

3. Recursive functions