QUERY · ISSUE

micropython dict has not contains method

openby bhcuong2008opened 2021-08-11updated 2021-08-12

py-core

Hi Team,

Today I check contains method of dict, but not found. MicroPython v1.16. I open file objdict.c, and also not found. Is it missed?

Thanks,
Cuong.

CANDIDATE · ISSUE

problems with contains magic method

closedby kimbautersopened 2014-06-10updated 2014-06-11

The magic method __contains__ seems to be defined in the micropython code, but it doesn't work. I have been trying to hunt down the problem and have failed to pinpoint it so far. The bug is easily reproducible:

class problem:
    def __contains__(self, key):
        return True

test = problem()
if True in test:
    print("__contains__ works")

Assessment

Q Qwen · high

Both issues concern the contains magic method and the 'in' operator, but they address different problems. Issue #7639 reports that the built-in dict type lacks contains support (a missing feature in the dict implementation). Issue #679 reports that contains is not being invoked for custom class instances (a runtime dispatch bug). These are distinct issues: one is about implementing contains for dict objects, the other is about the runtime mechanism for calling contains on user-defined classes. The candidate does not resolve the query about dict's missing contains method.

Suggested action

Keep both issues open. Issue #7639 needs __contains__ implementation in objdict.c. Issue #679 needs investigation of the runtime dispatch mechanism for __contains__ in custom classes.

micropython dict has not __contains__ method

problems with __contains__ magic method

Keyboard

micropython dict has not contains method

problems with contains magic method