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Specifies one or more parameters to pass during invocation of an ABL procedure, a user-defined function, a method of a class (ABL or .NET), a class constructor (ABL or .NET), or the built-in Publish( ) event method or PUBLISH statement to publish class or named events, respectively.
arguments (parm) . . .
A .NET mapped data type is any .NET primitive or object type that ABL maps implicitly to an ABL primitive type. For more information, see the Data types reference entry and Table 24.
For an ABL or .NET method, the parameter and argument data types must match exactly or map according to the widening rules of the target (on INPUT or OUTPUT) described in this entry. Also note that you cannot pass a System.Object on INPUT to a primitive parameter, because it is a typical narrowing case.
You cannot pass parameters where a Progress.Lang.Object is exchanged with a .NET mapped data type, because ABL does not do intermediate boxing or unboxing to a System.Object in order to exchange the value with a Progress.Lang.Object. However, you can pass parameters, exchanging a Progress.Lang.Object with a System.Object (with casting, as appropriate).
For an ABL routine, you cannot define parameters (or any data elements) directly as a .NET mapped data type (such as, System.Int32). To define parameters that take a .NET mapped type as an argument, you must use the matching ABL primitive type, as shown in Table 24 (such as, INTEGER). However, if an ABL method overrides a .NET method or implements a method of a .NET interface, you must define any .NET parameter that is a .NET mapped type using an ABL keyword (AS data type) that explicitly indicates this .NET type. Also note that this parameter functions at run time as its matching ABL primitive type, not the mapped type as defined by .NET. For more information, see the Parameter definition syntax reference entry.
ABL does not automatically box or unbox the value of a .NET System.Object or array object argument passed to a compatible ABL primitive or array parameter of an ABL routine. Also note that you cannot provide a Progress.Lang.Object argument to this parameter on OUTPUT, because an ABL primitive or array, even one with object type elements, is not an object itself and ABL does no boxing to a Progress.Lang.Object.
For an INPUT .NET array parameter of mapped type elements, because ABL does not have a unique primitive type to match each .NET mapped data type, ABL allows you to box any ABL array whose element type implicitly maps to the elements of the target .NET array, as shown in Table 24. For example, if the parameter is defined as a .NET "System.Int16[]" array object type, you can pass another "System.Int16[]" or an ABL INTEGER array to box, but you cannot pass an ABL INT64 array to box. On INPUT, you also cannot pass an ABL primitive array to a "System.Object[]" parameter, because ABL does not do automatic boxing at the element level of an array object.
If the parameter is defined as a .NET value type array (such as, "System.Drawing.Size[]"), the argument must be an identical .NET or ABL array type (such as "System.Drawing.Size[]" or System.Drawing.Size EXTENT). Also, while an INPUT System.Array parameter can take any appropriate .NET or ABL array argument, an INPUT "System.Object[]" parameter cannot take any ABL array (for .NET methods) or .NET array argument whose element type is an ABL primitive or .NET value type.
ABL does not automatically box or unbox a compatible ABL primitive or array data type passed to a corresponding .NET System.Object or array object parameter of an ABL routine. On INPUT, you can pass an ABL BOX function call taking a compatible ABL primitive or array type as input. On OUTPUT, you can provide a System.Object or compatible .NET array object argument and then convert it to an ABL primitive or array type by assigning or using the UNBOX function.
AS data-typeIndicates an explicit mapping between an argument with an ABL primitive type and the parameter of a .NET method or constructor. Assuming that the .NET data type defined for the parameter is compatible with the data type of the ABL argument, data-type represents an ABL keyword (AS data type) that indicates an alternative .NET data type mapping to identify with the .NET parameter. This option is necessary in the following cases:
iVal2 = System.Byte:MaxValue.iReturn = System.Math:Max( INPUT iVal1 AS UNSIGNED-BYTE,INPUT iVal2 AS UNSIGNED-BYTE ).The second fragment compiles, but returns a run-time error. Again, it passes the same two values to the System.Math:Max( ) method, but this time passes them as a System.SByte (specified by the AS data type, BYTE). A signed byte parameter cannot hold positive values as large as an unsigned byte. So, passing the maximum value of a System.Byte (unsigned byte) as a System.SByte (signed byte) causes the Max( ) method to raise a run-time overflow error:
iVal2 = System.Byte:MaxValue.iReturn = System.Math:Max( INPUT iVal1 AS BYTE,INPUT iVal2 AS BYTE ). /* Run-time error */The following code fragment shows an example of ABL data type widening when passing parameters to a .NET method. This example shows INPUT widening, in this case, passing different ABL data types (INTEGER and INT64) that are acceptable as arguments to a System.Double input parameter:
You can lose precision if you pass an ABL INTEGER or INT64 to a System.Single parameter.
Table 55 lists the .NET parameter data types for which ABL supports the widening of ABL data types passed as OUTPUT arguments. For each .NET parameter data type, the listed ABL implicit mapping data type represents the closest matching ABL data type that can hold a .NET value passed to the OUTPUT parameter defined with the matching .NET data type. The corresponding listed ABL OUTPUT widening data types might hold even larger values than the listed ABL implicit mapping data type. However, but they might also adhere to similar limitations as defined for the listed ABL implicit mapping data type (Again, see Table 24 for a more complete description of these limitations.)
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