Ignite: Improve deprecation messages

[vfdev-5]

🚀 Feature

House keeping request to improve the codebase.
The idea is to 1) improve deprecation messages inspired from scikit-image: https://github.com/scikit-image/scikit-image/blob/87a8806cca7fb5366b6e5ddbe5e46364b44f90fe/skimage/_shared/utils.py#L15-L214

            f"{self.arg_name} argument is deprecated and will be removed "
            f"in version {self.changed_version}. To avoid this warning, "
            f"please do not use the {self.arg_name} argument. Please "
            f"see {func.__name__} documentation for more details.")

and 2) introduce similar decorators in our codebase in a minimalistic way.

[pillemer]

Hey, I'm pretty new to contributing and I think this issue is something I can help you with.
The CONTRIBUTING.md is super detailed(!) so I'm feeling confident I can follow those instructions.
I'd like a to ask for little more specific detail about what is needed in this issue and where to look for the messages that need to be modified. As I understand it, the formatting of the current messages needs to be more simialr to the the one quoted? (short concise f-strings.)

[vfdev-5]

Hi @pillemer sorry for delayed reply ! The idea is to make sure that current deprecation messages like
https://github.com/pytorch/ignite/blob/96689c5f010c39115b76eaa3281af10fbc631ab0/ignite/contrib/engines/common.py#L277-L280
express a similar message:

• Aomething (e.g. function) is deprecated (we can keep the info since when it is deprecated)
• And will be removed in version vX.Y.Z
• To avoid this warning, please use something else (e.g. another function).

Currently, I found only one deprecation warning. Let's improve its message and for the others that I forgot.
We can not use f-strings as we still provide a support for python 3.5.
EDIT: we are not supporting python 3.5 since v0.5.0 => OK for the usage of f-strings (see https://github.com/pytorch/ignite/issues/1496)

Feel free to ask other questions if needed...

[afzal442]

We can not use f-strings as we still provide a support for python 3.5.

Hi, do you still provide support for python 3.5? Thanks.

[vfdev-5]

Hi, do you still provide support for python 3.5? Thanks.

@Afzal-Ind we just dropped the support of python 3.5 today.

[Devanshu24]

Hi @vfdev-5 !
I would like to give it a shot, if it is okay with you and if no one else is already working on it :)

PS: I did not know if I was supposed to tag you, sorry if I wasn't supposed to do that

[vfdev-5]

@Devanshu24 sure, sounds good ! Currently, no one is working on this issue. Let me assign it to you such that other would know. Feel free to ask questions to detail what we would like to implement if needed and send a draft PR that we could improve. Let me know if it sounds good for you too. Thanks !

[Devanshu24]

Sure sounds great, and thank you for the opportunity!
I'll get right to it. I will first find the current deprecation messages and understand the codebase a little, and will send a draft PR soon!

[Devanshu24]

One small question, where would we want to place all these decorators?
As in, inside utils.py or maybe a separate file in itself?

[vfdev-5]

I think ignite.utils.py can be a good place for that. If needed we can come back to this point in the PR.