How can I check if I can set (patch) attributes in Python objects

Question

Setting arbitrary attributes from outside works for normal classes, but not for internal objects like strings?! How can I check if I'm allowed to set arbitrary attributes?

Answer 1

Use try-except

def canSetAttr(o):
    try:
         name = 'probablynotset'
         flag = hasattr(o, name)
         if flag:
             old = getattr(o, name)
         setattr(o, name, 'x')
         if flag:
             setattr(o, name, old)
         else:
             delattr(o, name)

         return True
     except AttributeError:
         return False