coffeescript dictionary set default

Question

In Python if you have a dictionary that consists of lists like

   mydict = {'foo': [], 'bar':[3, 4]}

and if you want to add something into that lists you can do

   mydict.setdefault('baz', []).append(5)

not to write

key, list_element = 'baz', 5
if key in mydict:
    mydict[key].append(list_element)
else:
    mydict[key] = [list_element]

is there an equivalent for this in Coffeescript?

Answer 1

i recommend against using ||/ or to test for membership—it's basically a clever trick that will silently fail against falsy values. i prefer to write

( mydict[ name ]?= [] ).push value

which i find clearer; it assumes that in case mydict does not have an entry for name or that value is null or undefined, then an empty list should be put there at this point.