vbscript - 检查子函数或函数是否存在

Question

有没有办法检查子或函数是否存在？

sub mySub()
 'some code
end sub

类似于if exit(mySub)

Answer 1

更新:

所以我知道有一个更好的方法可以做到这一点，它使用 GetRef()

Function Exist(procName)
    On Error Resume Next
    Dim proc: Set proc = GetRef(procName)
    Exist = (Not proc Is Nothing)
End Function

Function Hello()
    WScript.Echo "Hello Ran"
End Function

If Exist("test") Then  'Returns False (0)
    WScript.Echo "Test Exists"
Else
    WScript.Echo "Test Doesn't Exist"
End If

If Exist("Hello") Then  'Returns True (-1)
    WScript.Echo "Hello Exists"
Else
    WScript.Echo "Hello Doesn't Exist"
End If

输出

Test Doesn't ExistHello Exists

---

There is nothing built into VBScript to do this but you can build something using On Error Resume Next and ExecuteGlobal().

Function Exist(procName)
    On Error Resume Next
    ExecuteGlobal "Call " & procName & "()"
    Exists = (Err.Number = 0)
End Function

Function Hello()
    WScript.Echo "Hello Ran"
End Function

If Exist("test") Then  'Returns False (0)
    WScript.Echo "Test Exists"
Else
    WScript.Echo "Test Doesn't Exist"
End If

If Exist("hello") Then  'Returns True (-1)
    WScript.Echo "Test Exists"
Else
    WScript.Echo "Test Doesn't Exist"
End If

输出

Test Doesn't ExistHello RanTest Doesn't Exist

这种方法的缺点是它实际上会运行该过程(如果存在)。