| Class Warfare [message #40433] |
Wed, 04 August 2004 14:31 |
Michael Wallace
Messages: 409
Registered: December 2003
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Senior Member |
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I'm using several Java classes in my IDL code and I'm attempting to make
the code a little more robust by doing some simple type checking of the
Java objects I'm sending into various procedures and methods. What I'm
after is something which does the same thing as the Java instanceof
operator. The OBJ_ISA function gets part of the way, but doesn't do an
entire instanceof check like Java does.
Here's an example... First create a Java string.
IDL> session = Obj_New('IDLjavaObject$IDLJAVABRIDGESESSION')
IDL> jstring = Obj_New('IDLjavaObject$java_lang_String', $
'java.lang.String', 'My String')
OBJ_ISA will tell you that it is a string, but doesn't tell you that it
is also an Object even though java.lang.String directly inherits from
java.lang.Object.
IDL> print, Obj_Isa(jstring, 'IDLjavaObject$java_lang_String')
1
IDL> print, Obj_Isa(jstring, 'IDLjavaObject$java_lang_Object')
0
In some situations there is a workaround. I can create a new Java
Object and get this object's Class and use that to test the Java string.
IDL> jobject = Obj_New('IDLjavaObject$java_lang_Object', $
'java.lang.Object ')
IDL> jobjcls = jobject -> GetClass()
IDL> print, jobjcls -> IsInstance(jstring)
1
While this works in a pinch, there are situations where this can't be
done to easily. There are classes which take time and/or resources to
instantiate and it doesn't make sense to instantiate a class only to
check if another class is an instance of it and not do anything else
with the class.
For the time being, I'm using OBJ_ISA with the exact class that I
expect, but it'd be much nicer to have some way to have a true Java
instanceof operator.
-Mike
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