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CheckInstanceOf Function

X#
Determine if an object is an instance of a particular class.

Namespace:  XSharp.RT
Assembly:  XSharp.RT (in XSharp.RT.dll) Version: 2.19
Syntax
 FUNCTION CheckInstanceOf(
	oObject AS Object,
	symClassName AS STRING
) AS LOGIC
Request Example View Source

Parameters

oObject
Type: Object
The object to check for.
symClassName
Type: String
The class that oObject may be an instance of.

Return Value

Type: Logic
TRUE if oObject is an instance of symClassName; otherwise, an error is generated. FALSE is returned if you choose to ignore the error. If oObject is a NULL_OBJECT, a FALSE is returned but no error is generated.
Remarks
An instance of an inherited class is also an instance of the original (super) class. However, an instance of a super class is not an instance of any of its inherited classes. CheckInstanceOf() is similar to IsInstanceOf(), except that it also generates an error message if the specified object is not an instance of the specified class.
Examples
These examples illustrate CheckInstanceOf() on inherited classes:
X#
 1CLASS Person
 2    EXPORT name, sign
 3CONSTRUCTOR(tName, tSign)
 4    name := tName
 5    sign := tSign
 6END CLASS
 7CLASS Male INHERIT Person
 8    EXPORT prefers
 9END CLASS
10FUNCTION CheckArgument()
11    LOCAL x, y AS OBJECT
12    x := Person{"Dude", "president"}
13    y := Male{"Charlie", "VP"}
14    ? CheckInstanceOf(x, #Person)        // TRUE
15    ? CheckInstanceOf(x, #Male)        // FALSE
16    ? CheckInstanceOf(y, #Person)        // TRUE
17    ? CheckInstanceOf(y, #Male)        // TRUE
See Also