Using an external comparator?

[egemenimre]

Hallo Alexandre,

I am currently working with an external library that provides an AbsoluteDate class. To compare these objects, it provides a comparator, but not the python native _gt_, _lt_ etc. Now I don't want to subclass it as it is rather core class and actually it is written in java - I am using it with a python wrapper. The java native project is Orekit and the Python wrapper is here. And with only a comparator I can't seem to use portion

I can do sorting etc. using key=functools.cmp_to_key(AbsoluteDate.compareTo), so the question is: Can I define an external key like this to portion, so that it knows how to compare things and works properly.

Otherwise I will be forced to subclass AbsoluteDate, add the usual comparison operators, and hope nothing breaks while jumping between java and python.

Thanks!

[AlexandreDecan]

Hi,

Unfortunately, there's no support for a cmp function for objects that do no support usual comparison operators. While the code of portion could possibly be changed to deal with such a function, doing so will make the code much less readable, so that's not an option I envision ;-)

Apart from subclassing AbsoluteDate, I don't see any other possibility :-/ I see there's an absolutedate_to_datetime function. Would it be possible to use this instead of AbsoluteDate instances?

[egemenimre]

I was hoping that you could set the config to support a key or cmp at the beginning, so that portion would know where to look at when it encountered an object of this type. Alas, if this would come at a large cost, then we can close the issue. Thanks!

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On Sat, 21 Jan 2023, 17:37 Alexandre Decan ***@***.***> wrote: Hi, Unfortunately, there's no support for a cmp function for objects that do no support usual comparison operators. While the code of portion could possibly be changed to deal with such a function, doing so will make the code much less readable, so that's not an option I envision ;-) Apart from subclassing AbsoluteDate, I don't see any other possibility :-/ I see there's an absolutedate_to_datetime function. Would it be possible to use this instead of AbsoluteDate instances? — Reply to this email directly, view it on GitHub <#74 (comment)>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/AO7QEK2JQ5LC3ZLRNHS74PTWTQGDRANCNFSM6AAAAAAUCMUEG4> . You are receiving this because you authored the thread.Message ID: ***@***.***>

[AlexandreDecan]

Unfortunately, that's not the case. portion supports "any object that is comparable" implicitly meaning "any object that supports <, >, etc." not cmp :-/ Sorry :-)

Supporting cmp might be useful in some circumstances, but I would say that it's probably better to open a PR on a project whose objects do not support the usual comparison operators, rather than to open a PR on portion to support these cases... :-/