Instantiating sub-class from super
On 2019-10-19 12:37 AM, DL Neil via Python-list wrote:
> On 16/10/19 6:33 PM, Frank Millman wrote:
>> On 2019-10-14 10:55 PM, DL Neil via Python-list wrote:
>>> Is there a technique or pattern for taking a (partially-) populated
>>> instance of a class, and re-creating it as an instance of one of its
>> Here is a link to an article entitled 'Understanding Hidden Subtypes'.
>> It dates back to 2004, but I think it is still relevant. It addresses
>> precisely the issues that you raise, but from a data-modelling
>> perspective, not a programming one.
>> I found it invaluable, and applied the concepts in my own
>> business/accounting application. Having created the ability to make
>> subtypes visible and explicit, I found all kinds of unexpected uses
>> for them.
>> The article seems to be missing a couple of images (Figure 1 and
>> Figure 2) showing the data relationships. I downloaded the original
>> article onto my computer years ago, and my local copy does have the
>> images, so if you would like to see them let me know and I will upload
>> my version somewhere to make it accessible.
> Yes please Frank - I've also approached it from the data/DB side, and
> thus presumably why I was puzzling over how one implements in Python.
> (alternatively, email a PDF/similar directly)
I have just got back from a few days break and have only seen your
Did you see the message I posted on the 17th with a download link? If
not, would you like me to post it again?