VBA: Access to registry while preprocessing

问题

I want to conditionally compile code in one VBAproject, with a condition that depends on some registry-entry. Is this somehow possible in VBA?

I know that there are some simple preprocessing possibilites in VBA, but I can not see if it is possible to somehow access the registry while preprocessing. Or Maybe some other possibility to check the registry before compiling.

Since I get a compile error because of some missing reference(and thus missing class object), I aim to check the registry before compiling.

P.s. I only want to read registry-entries.

As an example. How to reach debug.print in the following, i.e. avoiding compile errors.

sub sub1()
   dim testobj as new nonexistingobject
   sub2 testobj
   debug.print "Arrived at this point"
end sub

sub sub2( byref testobj as nonexistingobject)
   *do some stuff with testobj*
end sub

回答1:

Instead of using early binding (Dim obj as myObject), use late bindings with CreateObject. This way you will be able to handle the case where the object doesn't exists:

Sub test()
    Dim obj As Object
    On Error Resume Next
    obj = CreateObject("myObject")
    if Err then Exit Sub 'if the object wasn't found exit the function
    on error goto 0 'set back the error handling to its previous state

    'rest of the code
End Sub

回答2:

VBA does not directly provide access to the entire Windows Registry, but you can use a workaround.

Dim RegObj as Object
Set RegObj = CreateObject("WScript.Shell")

RegObj.RegDelete RegKeyString
RegObj.RegWrite RegKeyString
Str = RegObj.RegRead RegKeyString

Set RegObj = Nothing

If the RegKeyString is not found, it'll throw an error, so you need some OnError -> Key Doesn't Exist kind of code.

Not sure of the preprocessing part, but you could run your code in the Workbook_Open event handler to make sure this part runs before anything else.

回答3:

It is not feasible. All the symbols and conditions that are tested by VBA Directives are build from literals or expressions that include only operators (excepting the Is operator, I think).

Function calls are not allowed when declaring directive symbols and conditions, and the only way to access registry in VBA is via API (like WScript.Shell for example), which means function call.

Further reading: http://msdn.microsoft.com/en-us/library/tx6yas69.aspx

来源：https://stackoverflow.com/questions/24558164/vba-access-to-registry-while-preprocessing