vbscript Eval a string to a Variable in a loop?

问题:

I am trying to use vbscript's Eval (or maybe I need Execute) to create some variables from the key names from an ini file. The ini file can have unlimited unknown key=val pairs. I need to create a variable based on the key name no matter what.

Ini File contents:

myPath=c:\test
myExe=myapp.exe
....
xxx=123
yyy=abc

My code that reads the ini and returns the key and values to an object

The code I am trying to get working is here:

For each pair in objINI
    Eval("pair.key=pair.val")
Next

msgbox myPath
msgbox myExe

But both msgbox's are showing empty And yes I am sure pair.key and pair.val have the correct values.

Thoughts on what I am missing or if this is even possible?

回答1:

You eval'd the literal code pair.key = pair.value.
That assigns to pair.key.

You want to assign to the value of pair.key – if pair.key is myPath, you want to eval myPath = pair.value.
You can do that by concatenating strings:

Execute(pair.name + " = pair.value")

回答2:

You need to Execute (an assign statement), not to Eval(uate a boolean expression):

>> n = "Name"
>> v = "Value"
>> WScript.Echo TypeName(Eval("n=v"))
>>
Boolean
>> Execute "n=v"
>> WScript.Echo n
>>
Value
>>

From the docs:

In VBScript, x = y can be interpreted two ways. The first is as an assignment statement, where the value of y is assigned to x. The second interpretation is as an expression that tests if x and y have the same value. If they do, result is True; if they are not, result is False. The Execute statement always uses the first interpretation, whereas the Eval method always uses the second.

(This does not mean you should do such things; neither at home, nor at work)

回答3:

If you want to read key/value pairs from an INI file you'd be better off storing them in a dictionary. I wrote a function for this some years ago. Basically looks like this:

Function ParseIni(filename)
  Set ParseIni = Nothing

  Set config = CreateObject("Scripting.Dictionary")
  section = ""

  Set file = CreateObject("Scripting.FileSystemObject").OpenTextFile(filename)
  Do While Not file.AtEndOfStream
    line = Trim(Replace(file.ReadLine, vbTab, " "))
    If InStr(line, ";") > 0 Then line = Trim(Left(line, InStr(line, ";") - 1))
    If line <> "" Then
      If Left(line, 1) = "[" And Right(line, 1) = "]" Then
        ' line is a section name
        section = Trim(Mid(line, 2, Len(line) - 2))
        If section = "" Then _
          WScript.Echo "Parse Error: section name is empty string."
        If config.Exists(section) Then _
          WScript.Echo "Parse Error: duplicate section name '" & name & "'."
        config.Add section, CreateObject("Scripting.Dictionary")
      ElseIf InStr(line, "=") > 0 Then
        ' line is a parameter line
        If section = "" And Not config.Exists(section) Then _
          config.Add section, CreateObject("Scripting.Dictionary")
        param = Split(line, "=", 2)
        param(0) = Trim(param(0))
        param(1) = Trim(param(1))
        If param(0) = "" Then _
          WScript.Echo "Parse Error: invalid parameter name '" & param(0) & "'."
        If param(1) = "" Then param(1) = True
        config(section).Add param(0), param(1)
      Else
        ' line is neither parameter nor section name, thus invalid
        WScript.Echo "Parse Error: expected parameter definition in line '" _
          & line & "'."
      End If
    End If
  Loop
  file.Close

  Set ParseIni = config
End Function