QUERY · ISSUE

deepcopy function references a non-existant variable

openby dhylandsopened 2018-05-23updated 2019-02-21

In copy.py: https://github.com/micropython/micropython-lib/blob/f20d89c6aad9443a696561ca2a01f7ef0c8fb302/copy/copy.py#L163 the deepcopy function references the variable dispatch_table, which isn't initialized.

2 comments

harryofskyrim · 2019-02-21

SO? The issue is still present, and it's really unpleasant

dhylands · 2019-02-21

I just reported this on pfalcon's repository which is the "official" source of this repository.
https://github.com/pfalcon/micropython-lib/issues/26

CANDIDATE · PULL REQUEST

copy: Add stub dispatch_table for use in copy().

closedby andrewleechopened 2020-06-16updated 2025-11-19

copy() depends on dispatch_table which was previously / cpython imported from copyreg module.
Without this module the attribute is not available when copy() function tries to check it.

1 comment

andrewleech · 2025-11-19

Fixed in 0b78a15

Assessment

S Sonnet · medium

Both the issue and the PR concern the same root cause: dispatch_table is undefined in copy.py because the copyreg module (which defines it in CPython) is not available in MicroPython. PR #391 fixes this by adding a stub dispatch_table = {} at the module level. The issue reports the NameError in deepcopy, while the PR describes the fix as targeting copy() — but a module-level stub would resolve the NameError in both functions. The mismatch in the described function introduces some uncertainty about whether the PR fully covers the deepcopy code path at line 163.

Suggested action

Confirm PR #391 is merged and that the stub `dispatch_table` is placed at module scope (making it accessible to `deepcopy` as well as `copy`). If so, close issue #281 as resolved by PR #391.

deepcopy function references a non-existant variable

copy: Add stub dispatch_table for use in copy().

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