PyQt from py27 to py38

Wed Oct 27 08:55:30 BST 2021

Here is an example of how we do it for PyQt5→PyQt6:

https://github.com/ankitects/anki/blob/036d04a7b1514fde0018280a79e98066275dae9c/qt/aqt/profiles.py#L159

You might be able to adapt it for PyQt4 as well. In our case we were
incorrectly storing the pickled data back in the Python 2 days, so couldn't
safely bring it into PyQt5.

On Wed, Oct 27, 2021 at 3:07 AM Tomas Sobota <tom at sobota.net> wrote:

> A couple of ideas here:
>
> https://stackoverflow.com/questions/54047757/unpickle-binary-file-to-text/54048296#54048296
> Maybe you could take it from there?
> Tom
>
> On Tue, Oct 26, 2021 at 6:12 PM RoadrunnerWMC <roadrunnerwmc at gmail.com>
> wrote:
>
>> (Just adding this to the mailing list, if you don't mind)
>>
>> ---------- Forwarded message ---------
>> From: Nicola Raffo <nicola.raffo at rulex.ai>
>> Date: Tue, Oct 26, 2021 at 11:15 AM
>> Subject: Re: PyQt from py27 to py38
>> To: RoadrunnerWMC <roadrunnerwmc at gmail.com>
>>
>>
>> Similar scenario here, I have to deal with some data stored with pickled
>> PyQt4 objects. The pickletools method can be useful to "read" the pickled
>> data, but I need a conversion from PyQt4 to PyQt5 data in order to be able
>> to load the data in Python 3.8 and whitout a proper method to do it I can't
>> depickle data in Python 3.8.
>>
>> Another idea could be to use the previous version of the code which still
>> uses python 2.7 and to store them in another format, but this could take a
>> long time.
>>
>> What I need is a tool that allows me to automatically read and open these
>> data in Python 3.8
>> ------------------------------
>> *From:* RoadrunnerWMC <roadrunnerwmc at gmail.com>
>> *Sent:* 26 October 2021 17:06
>> *To:* Florian Bruhin <me at the-compiler.org>
>> *Cc:* pyqt at riverbankcomputing.com <pyqt at riverbankcomputing.com>
>> *Subject:* Re: PyQt from py27 to py38
>>
>> The pickletools method is at least doable for relatively simple pickles
>> -- I have an application that does exactly that because another developer
>> made the less-than-wise decision to store pickled PyQt4 objects in user
>> data files a long time ago, and now I have to support reading them forever.
>> The main downside is that you have to make a lot of assumptions about the
>> structure of the pickle data, ones which technically don't *need* to
>> always be true, but *should* nevertheless be safe if your users are all
>> using CPython and not manually messing with the generated pickle data for
>> some reason.
>>
>> There is another option, too, which is to make a minimal fake "PyQt4"
>> interface (just a few nearly-empty class stubs) and have pickle load using
>> that. I chose the pickletools method because of the additional security
>> benefits of avoiding using pickle.loads() on untrusted user data files.
>>
>> On Tue, Oct 26, 2021 at 8:58 AM Florian Bruhin <me at the-compiler.org>
>> wrote:
>>
>> On Tue, Oct 26, 2021 at 11:47:40AM +0200, Florian Bruhin wrote:
>> > The harder way is to somehow coerce pickle into giving you the "raw"
>> > data without the PyQt object involved...
>>
>> I just learned there's 'pickletools' in the stdlib:
>> https://docs.python.org/3/library/pickletools.html
>> <https://nam12.safelinks.protection.outlook.com/?url=https%3A%2F%2Fdocs.python.org%2F3%2Flibrary%2Fpickletools.html&data=04%7C01%7Cnicola.raffo%40rulex.ai%7C74001822c1bd4a9803f308d998924bf9%7Ccb4c9caf154d430fade0c36c8af22d19%7C0%7C0%7C637708576448192165%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C1000&sdata=rJY1OaBWAhzGQtPg9t%2BFsHUBVfL%2BkWiOBv%2BdLUt%2Bung%3D&reserved=0>
>>
>> Using that, you could inspect the pickle manually and pick the data out
>> of it somehow. Given how pickles are structured, not exactly
>> straightfoward either, though.
>>
>> Florian
>>
>> --
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>> --
>>
>> *Nicola Raffo*
>>
>> Senior Product Development Specialist
>>
>> RuleX <https://rulex.ai>
>>
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