How to: Qualify a Declared Element Name

Articolo
11/18/2006

When your code refers to a declared element, the Visual Basic compiler must match the name in your reference to the appropriate declaration of that name. If the element is defined outside your code, or if more than one element is declared with the same name, you might need to qualify the name to allow the compiler to resolve any possible ambiguity or to locate the element.

Qualifying a name means preceding it in your source statement with information that identifies where the target element is defined. This information is called a qualification string. It can include one or more namespaces and a module, class, or structure.

The qualification string should unambiguously specify the module, class, or structure containing the target element. The container might in turn be located in another containing element, usually a namespace. You might need to include several containing elements in the qualification string.

To access a declared element by qualifying its name

Determine the location in which the element has been defined. This might include a namespace, or even a hierarchy of namespaces. Within the lowest-level namespace, the element must be contained in a module, class, or structure.

' Assume the following hierarchy exists outside your code.
Namespace outerSpace
    Namespace innerSpace
        Module holdsTotals
            Public Structure totals
                Public thisTotal As Integer
                Public Shared grandTotal As Long
            End Structure
        End Module
    End Namespace
End Namespace

Determine a qualification path based on the target element's location. Start with the highest-level namespace, proceed to the lowest-level namespace, and end with the module, class, or structure containing the target element. Each element in the path must contain the element that follows it.

outerSpace → innerSpace → holdsTotals → totals
Prepare the qualification string for the target element. Place a period (.) after every element in the path. Your application must have access to every element in your qualification string.
```
outerSpace.innerSpace.holdsTotals.totals.
```
Write the expression or assignment statement referring to the target element in the normal way.
```
grandTotal = 9000
```

Precede the target element name with the qualification string. The name should immediately follow the period (.) that follows the module, class, or structure that contains the element.

' Assume the following module is part of your code.
Module accessGrandTotal
    Public Sub setGrandTotal()
        outerSpace.innerSpace.holdsTotals.totals.grandTotal = 9000
    End Sub
End Module

The compiler uses the qualification string to find a clear, unambiguous declaration to which it can match the target element reference.

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How to: Qualify a Declared Element Name

To access a declared element by qualifying its name

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