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From: Armin Zingler on 9 Apr 2010 10:13 Am 09.04.2010 14:18, schrieb Scott: > I normally do use byval as a default... > > Normally the only reasons I use ByRef is either to change something > like you said, or also if the object is very large like a huge dataset > or something it seems like a waste to make a copy of it. You don't make a copy of a Dataset if you pass it ByVal. You make a copy of the variable content, and that's just the reference (32/64 bits) to the DataSet. -- Armin
From: Patrice on 9 Apr 2010 11:26 > Normally the only reasons I use ByRef is either to change something > like you said, or also if the object is very large like a huge dataset > or something it seems like a waste to make a copy of it. Objects are pointers. ByVal, ByRef is just about the pointer, not the data this pointer points to : Sub ByValTest(ByVal o As SomeObject) o.MyProperty="A" ' This change will be seen in the main code (access is done using a copy of the pointer but it still points to the same location) o=Nothing ' You set the copy of the pointer itself to 0, this change won't be seen in the main code as you modify a copy of the pointer value End Sub Sub ByValRef(ByRef o As SomeObject) o.MyProperty="B" ' This change will be seen in the main code (access is done using the pointer and it still points to the same location) o=Nothing ' Will set also the argument to nothing as here you are working on the real value of the pointer, not on a copy... End Sub ByVal/ByRef doesn't change the behavior when you modify the object data. It differs only when you change the object variable itself... -- Patrice
From: Cor Ligthert[MVP] on 10 Apr 2010 09:52
And to add to the answer from Armin, Especially with a dataset you will almost never use the ByRef. With the dataset it is common practice to use either the Fill or a function like GetDataset. The later function creates always a new dataset and returns the reference of that ByVal, while the Fill fills the dataset which is referenced in the ByVal. Cor "Armin Zingler" <az.nospam(a)freenet.de> wrote in message news:urE0H8#1KHA.5880(a)TK2MSFTNGP05.phx.gbl... > Am 09.04.2010 14:18, schrieb Scott: >> I normally do use byval as a default... >> >> Normally the only reasons I use ByRef is either to change something >> like you said, or also if the object is very large like a huge dataset >> or something it seems like a waste to make a copy of it. > > You don't make a copy of a Dataset if you pass it ByVal. You make > a copy of the variable content, and that's just the reference (32/64 bits) > to the DataSet. > > > -- > Armin |