I have a list of objects which I want to turn into a set. My objects contain a few fields that some of which are o.id
and o.area
. I want two objects to be equal if these two fields are the same. ie: o1==o2
if and only if o1.area==o2.area and o1.id==o2.id
.
I tried over-writing __eq__
and __cmp__
but I get the error: TypeError: unhashable instance
.
What should I over-write?