Cannot overwrite the __str__ method in jitclass

[pietrodantuono]

Hello,

I am not able to overwrite the string representation of a jitclass. I do not know if this is a wanted behaviour though.

from numba.experimental import jitclass
from numba import float64

spec = [("alpha", float64)]


@jitclass(spec)
class Foo:
    def __init__(self, alpha):
        self.alpha = alpha
    
    def __str__(self):
        return "Class Foo"


foo = Foo(1.)

print(str(foo))

Produces:

<numba.experimental.jitclass.boxing.Foo object at 0xS0M3wh3r3>

Expected:

Class Foo

It seems that the __str__() method is skipped entirely, in fact the following does not produce any ZeroDivisionError.

...
    def __str__(self):
        return 0 ** (-2)

Tested on:

Platform: Linux-5.15.0-52-generic-x86_64-with-glibc2.35
Python version: 3.9.7 (default, Sep 20 2022, 16:21:01) 
[GCC 11.2.0]

Numba version: 0.55.2

[stuartarchibald]

Thanks for the report @pietrodantuono. I think this was implemented in 0.56:

numba/CHANGE_LOG

Lines 80 to 84 in f4b6fe0

	Numba specific feature enhancements:
	* The experimental ``jitclass`` feature gains support for a large number of
	``builtin`` methods e.g. declaring ``__hash__`` or ``__getitem__`` for a
	``jitclass`` type.

and it (jitclass __str__ method) seems to work for me locally on main. If you can, perhaps try updating to 0.56 and seeing if that now works as expected with the above?

[pietrodantuono]

Thank you @stuartarchibald! After updating to 0.56.3, the __str__ method works!

My bad, I did not notice it from the Release notes

Numba specific feature enhancements:

The experimental jitclass feature gains support for a large number of builtin methods e.g. declaring __hash__ or __getitem__ for a jitclass type.

(https://numba.readthedocs.io/en/stable/release-notes.html#version-0-56-0-25-july-2022)

Next question: what about __repr__? Any possibility for it to be implemented in a future release?
It'd be really nice to have it for usage within Jupyter Notebook.

[stuartarchibald]

Thank you @stuartarchibald! After updating to 0.56.3, the __str__ method works!

My bad, I did not notice it from the Release notes

No problem, glad it is working now.

Next question: what about __repr__? Any possibility for it to be implemented in a future release? It'd be really nice to have it for usage within Jupyter Notebook.

I suggest opening a feature request if it is important to you. I think it's technically possible to support it.

[pietrodantuono]

Done!

Ref. #8533

[stuartarchibald]

Done!

Ref. #8533

Great, many thanks. I'll close this issue as resolved.