Question

I want to do something like this:

parsetable = {
              # ...

              declarations: {
                             token: 3 for token in [_id, _if, _while, _lbrace, _println]
                             }.update({_variable: 2}),

              #...
             }

However this doesn’t work because update doesn’t return anything. Is there any easy way to do this besides writing the entire dict explicitly?

It should be possible using dict() and a list comprehension of tuples + the extra part, but that is awkward.

Answer 1

I think the approach you mentioned using dict() and a list of tuples is the way I would do it:

dict([(x, 3) for x in [_id, _if, _while, _lbrace, _println]] + [(_variable, 2)])

If you really want to use a dict comprehension you can do something like this:

{ x : 2 if x == _variable else 3
  for x in [_id, _if, _while, _lbrace, _println, _variable] }