Q re Shared Methods

[Simon Woods]

Hi

I'm pretty new to vb.net and have a question because I'm not sure when to
use Shared as part of the method declaration. I understand, from my reading,
that this applies the method to the class rather than each object created
from that class, but I don't understand the applicability of this.

So for example, I have a business object working in the middle tier. I have
a collection class, MyBusinessObjec ts, which has a Function GetData and
returns a MyBusinessObjec t.

e.g.

Public Class MyBusinessObjec ts

Public Function GetData(KeyList () as String) as MyBusinessObjec t
....

or

Public Shared Function GetData(KeyList () as String) as
MyBusinessObjec t
...
End Class

So when I'm using this collection in my code, I could

Dim _MyBusinessObje cts as New MyBusinessObjec ts
For Each _MyBusinessObje ct as MyBusinessObjec t in
_MyBusinessObje cts.GetData(Key list())
...
Next

or using the Shared declaration I could

For each _MyBusinessObje ct as MyBusinessObjec t in
MyBusinessObjec ts.GetData(Keyl ist())
...
Next

Perhaps my example isn't a very good one, but when should I use Shared and
when not?

Thanks

Simon

[Mattias Sjögren]

Re: Q re Shared Methods

>Perhaps my example isn't a very good one, but when should I use Shared and

>when not?

You can use Shared whenever the method doesn't depend on any instance
data or method.


Mattias

--
Mattias Sjögren [C# MVP] mattias @ mvps.org
http://www.msjogren.net/dotnet/ | http://www.dotnetinterop.com
Please reply only to the newsgroup.

[Phill W.]

Re: Q re Shared Methods

Simon Woods wrote:

I'm pretty new to vb.net and have a question because I'm not sure when to
use Shared as part of the method declaration. I understand, from my reading,
that this applies the method to the class rather than each object created
from that class, but I don't understand the applicability of this.

Consider the String class.

Dim s As String = "a,b,c,d,e"
Dim array() as String _
= s.Split( "," )

Here, you're using an Instance method (Split) that relies on the data
held in the /specific/ String object that it's called on.

s = String.Format( "{0},{1},{2 }" _
array(0), array(1), array(2) )

This is using the Shared method, Format. Format doesn't operate on any
specific String, but it's "related" to other String-like operations so
the logical place to put it is in the String class.

HTH,
Phill W.

[Simon Woods]

Re: Q re Shared Methods

Thanks Phill and Mattias

Phill W. wrote:

Simon Woods wrote:
>

>I'm pretty new to vb.net and have a question because I'm not sure
>when to use Shared as part of the method declaration. I understand,
>from my reading, that this applies the method to the class rather
>than each object created from that class, but I don't understand the
>applicabilit y of this.

>
Consider the String class.
>
Dim s As String = "a,b,c,d,e"
Dim array() as String _
= s.Split( "," )
>
Here, you're using an Instance method (Split) that relies on the data
held in the /specific/ String object that it's called on.
>
s = String.Format( "{0},{1},{2 }" _
array(0), array(1), array(2) )
>
This is using the Shared method, Format. Format doesn't operate on
any specific String, but it's "related" to other String-like
operations so the logical place to put it is in the String class.
>
HTH,
Phill W.