如何在 VBA 中动态引用对象属性

Question

我正在尝试编写一个 VBA 函数，该函数根据对象属性之一的值对集合中的对象进行计数。我需要检查的对象属性是动态的，由函数参数提供。我可以使用if then 语句，但这会有很多很多elseif 子句，每个子句都有相同的过程，除了属性名称。

我想避免为每个属性名称一遍又一遍地重复我的代码。这是我目前所拥有的。

Private Function getTicketCount(c As Collection, f As String, s As String) _
 As Long
' @param c: collection of Ticket objects.
' @param f: property to filter.
' @param s: filter string.
'
' Function returns number of tickets that pass the filter.

Dim x As Long
Dim t As Ticket

x = 0

For Each t In c
    If t.f = s Then x = x + 1 ' Compiler throws "Method or data member not found."
Next t

getTicketCount = x
End Function

我遇到的问题是编译器正在寻找 t 的“f”属性而不是 t 的 value-of-f 属性。确切的错误在上面的代码块中进行了注释。如何使用 f 的值而不是“f”来引用对象属性？

Answer 1

相信你想使用CallByName方法CallByName MSDN Link

Private Function getTicketCount(c As Collection, f As String, s As String) _
 As Long
' @param c: collection of Ticket objects.
' @param f: property to filter.
' @param s: filter string.
'
' Function returns number of tickets that pass the filter.

Dim x As Long
Dim t As Ticket

x = 0

For Each t In c
    If CallByName(t, f, VbGet) = s Then x = x + 1 ' Compiler throws "Method or data member not found."
Next t

getTicketCount = x
End Function