Problem using '=' with System.Type
in [VB.NET]
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From: John on 22 Mar 2010 21:27 Hi I have the following code; ByVal MyType As Type Dim frame As StackFrame If frame.GetMethod().DeclaringType = MyType Then Problem is I am getting the "Operator '=' is not defined for types 'System.Type' and 'System.Type'." error on the last line. How can I fix this? Thanks Regards
From: Armin Zingler on 22 Mar 2010 21:38 Am 23.03.2010 02:27, schrieb John: > Hi > > I have the following code; > > ByVal MyType As Type > Dim frame As StackFrame > If frame.GetMethod().DeclaringType = MyType Then > > Problem is I am getting the "Operator '=' is not defined for types > 'System.Type' and 'System.Type'." error on the last line. How can I fix > this? To compare references, use the 'Is' operator: If frame.GetMethod().DeclaringType Is MyType -- Armin
From: Göran Andersson on 23 Mar 2010 04:31 John wrote: > Hi > > I have the following code; > > ByVal MyType As Type > Dim frame As StackFrame > If frame.GetMethod().DeclaringType = MyType Then > > Problem is I am getting the "Operator '=' is not defined for types > 'System.Type' and 'System.Type'." error on the last line. How can I fix > this? > > Thanks > > Regards > VB has it's own implementation of the = operator, so it doesn't always work as you might expect. Use the Equals method to use it's own built in comparison to compare the types: If frame.GetMethod().DeclaringType.Equals(MyType) Then -- G�ran Andersson _____ http://www.guffa.com
From: Göran Andersson on 23 Mar 2010 04:34 Armin Zingler wrote: > Am 23.03.2010 02:27, schrieb John: >> Hi >> >> I have the following code; >> >> ByVal MyType As Type >> Dim frame As StackFrame >> If frame.GetMethod().DeclaringType = MyType Then >> >> Problem is I am getting the "Operator '=' is not defined for types >> 'System.Type' and 'System.Type'." error on the last line. How can I fix >> this? > > To compare references, use the 'Is' operator: > > If frame.GetMethod().DeclaringType Is MyType > The Is operator works for some purposes, but it doesn't do an equality comparison. For example, (String Is Object) = True, while (Object Is String) = False. -- G�ran Andersson _____ http://www.guffa.com
From: Armin Zingler on 23 Mar 2010 07:27
Am 23.03.2010 09:34, schrieb G�ran Andersson: > Armin Zingler wrote: >> Am 23.03.2010 02:27, schrieb John: >>> Hi >>> >>> I have the following code; >>> >>> ByVal MyType As Type >>> Dim frame As StackFrame >>> If frame.GetMethod().DeclaringType = MyType Then >>> >>> Problem is I am getting the "Operator '=' is not defined for types >>> 'System.Type' and 'System.Type'." error on the last line. How can I fix >>> this? >> >> To compare references, use the 'Is' operator: >> >> If frame.GetMethod().DeclaringType Is MyType >> > > The Is operator works for some purposes, but it doesn't do an equality > comparison. For example, (String Is Object) = True, while (Object Is > String) = False. Help me understanding it. :) John wants to check if it's the same System.Type object, right? So your example with String and Object would be: dim t1 = gettype(string) dim t2 = gettype(object) msgbox (t1 is t2) 'False msgbox (t2 is t1) 'False He does not want to check if the type of an object is of a certain type or derived from that type. But maybe I got it wrong. -- Armin |