MappingProxyType is another handy one. It wraps a regular dict/Mapping to create a read-only live view of the underlying dict. You can use it to expose a dict that can't be modified, but doesn't need copying.

https://docs.python.org/3/library/types.html#types.MappingPr...

what do people use when they want shorthand for something like this:

  a['foo'] = 20
  a['bar'] = 9

where you want to be able to do:

  a.foo = 20
  a.bar = 9

    a = vars(a) # readonly
    print(a.foo)

    class Obj: pass; 
    a = Obj()
    a.foo = 20