can we use string as expression in if statement in vb.net

Hi all,

         I want to use if statement and i am reading condition/expression from text file and storing in a string/object variable.

now i want use that string/object as my condition in if statement like below.

Dim sourceLogic as String ="reading from a text file"

if sourceLogic then

'do something

End If

can we use like above.

please help me.