On Wed, Jan 10, 2018 at 04:08:04PM +0000, Albert-Jan Roskam wrote:
> In another thread on this list I was reminded of
> types.SimpleNamespace. This is nice, but I wanted to create a bag
> class with constants that are read-only.
If you expect to specify the names of the constants ahead of time, the
best solution is (I think) a namedtuple.
from collections import namedtuple
Bag = namedtuple('Bag', 'yes no dunno')
a = Bag(yes=1, no=0, dunno=42)
b = Bag(yes='okay', no='no way', dunno='not a clue')
ought to do what you want.
Don't make the mistake of doing this:
from collections import namedtuple
a = namedtuple('Bag', 'yes no dunno')(yes=1, no=0, dunno=42)
b = namedtuple('Bag', 'yes no dunno')(yes='okay', no='no way', dunno='not a
clue')
because that's quite wasteful of memory: each of a and b belong to a
separate hidden class, and classes are rather largish objects.
If you expect to be able to add new items on the fly, but have them
read-only once set, that's a different story.
--
Steve
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