无法访问VB.Net中的属性的索引器

Question

I have a property Cmd defined as follows

Private _cmd As ADODB.Command

Public ReadOnly Property Cmd() As ADODB.Command
    Get
        Cmd = _cmd
    End Get
End Property

However, when I try to use it like this:

y = x.Cmd("abc")

I get:

Overload resolution failed because no accessible 'Parameters' accepts this number of arguments.

However, this works:

y = (x.Cmd)("abc")

Can I change my property definition so that the user does not need the parens?

Answer 1

In addition to binarycoder´s solution, I suggest you another one. If you want to use your code in this way:

y = x.Cmd("abc")

You can change your Cmd property to look like this:

Public ReadOnly Property Cmd(ByVal parameterName As String) As ADODB.Command
        Get
            Return _cmd.Parameters(parameterName)
        End Get
End Property

Hope it helps!

Answer 2

Can I change my property definition so that the user does not need the parens?

No. The crux of the issue is that the default property ( Parameters ) is not an indexed property but instead returns an ADODB.Parameters object. Although ADODB.Parameters is has indexed Item property, it is one level too deep. Since you can't change ADODB , you might consider adding a helper method. You can then use this method instead of your property.

Public Function CmdParameter(ByVal parameterName As String) As ADODB.Parameter
    Return Cmd.Parameters(parameterName)
End Function