checking whether the current object is a specific class.
in [VB.NET]
|
Prev: Datagridview selected rows
Next: Inheritance and COM
From: Mr. X. on 10 Jun 2010 15:36 Hello. I need to check whether the current object Is a specific class, For example : function a(b as object) ' I need to check here, whether b is Button class. ' How can I do that ? end function Thanks :)
From: Armin Zingler on 10 Jun 2010 15:55 Am 10.06.2010 21:36, schrieb Mr. X.: > Hello. > I need to check whether the current object Is a specific class, > > For example : > function a(b as object) > ' I need to check here, whether b is Button class. > ' How can I do that ? > end function > > Thanks :) What's your intention? -- Armin
From: Onur Güzel on 10 Jun 2010 16:03 On Jun 10, 10:36 pm, "Mr. X." <nospam(a)nospam_please.com> wrote: > Hello. > I need to check whether the current object Is a specific class, > > For example : > function a(b as object) > ' I need to check here, whether b is Button class. > ' How can I do that ? > end function > > Thanks :) Use: If TypeOf b Is Button Then ' ..... End If HTH, Onur Güzel
From: Mr. X. on 10 Jun 2010 17:13 Thanks :) "Onur G�zel" <kimiraikkonen85(a)gmail.com> wrote in message news:f75ba3ec-eefe-411a-84eb-1e96c20702c1(a)c33g2000yqm.googlegroups.com... > On Jun 10, 10:36 pm, "Mr. X." <nospam(a)nospam_please.com> wrote: >> Hello. >> I need to check whether the current object Is a specific class, >> >> For example : >> function a(b as object) >> ' I need to check here, whether b is Button class. >> ' How can I do that ? >> end function >> >> Thanks :) > > Use: > > If TypeOf b Is Button Then > ' ..... > End If > > HTH, > > Onur G�zel
From: Phill W. on 11 Jun 2010 06:50
On 10/06/2010 20:36, Mr. X. wrote: > I need to check whether the current object Is a specific class, > For example : > function a(b as object) Why? Bear with me: It's not as silly a question as it sounds; it depends on what you want to /do/ with it once you've found it. (1) If you want a method that, say, enables or disables the control that you pass to it, but you want it to work for lots of different Types of Control (contrived, but a common thing to do), use overloading: Function Z( byval btn as Button, byval enabled as Boolean ) Function Z( byval tb as TextBox, byval enabled as Boolean ) Function Z( byval cmb as ComboBox, byval enabled as Boolean ) When you code Z( Me.Button3 ) the compiler works out /which/ method to call. (2) If you need to work out what Type of control you've got in, say, an Event Handler, use TypeOf: Sub Thing_Click( byval sender as Object, byval e as EventArgs ) _ Handles ... If TypeOf sender Is TextBox Then With DirectCast( sender, textBox ) . . . End With End If End Sub If you're testing for lots of Types, you still need a chain of If .. Else's; you can't use TypeOf with Select .. Case. (3) If you need to detect subclasses of a given Type, things get a bit more fiddly: If thing.GetType().IsSubClassOf( SomeType ) Then ' thing is a subclass of SomeType ' but not SomeType itself. . . . End If HTH, Phill W. |