Yeah it makes sense the default_factory argument in the field object could be utilized to support early bound defaults.
> On 26 Nov 2021, at 10:42 PM, Christopher Barker <python...@gmail.com> wrote: > > dataclasses use Field objects that can be created automatically, but also you > can specify them if you need to do something special. And one of the special > things you can do is set a default constructor -- I'm sure that could be > extended to support early bound defaults. > > -CHB > > > On Thu, Nov 25, 2021 at 11:40 PM Chris Angelico <ros...@gmail.com > <mailto:ros...@gmail.com>> wrote: > On Fri, Nov 26, 2021 at 6:22 PM Abdulla Al Kathiri > <alkathiri.abdu...@gmail.com <mailto:alkathiri.abdu...@gmail.com>> wrote: > > > > Chris, > > > > Will we able to use late-bound arguments in dataclass when it’s creating > > the __init__ function? > > > > @dataclass > > class C: > > x: int > > y: int > > ls: list[int] => [x, y] > > > > With that syntax, no, because there's no object that can be stored in > an annotation dictionary that would represent the code construct to > create that effect. > > But the __init__ function is constructed with exec(), and that means > that, in theory, dataclasses._field_init could be enhanced to have > some way to indicate this - or, possibly, to *always* use late-bound > defaults, since it appears to use sentinels for everything. > > I don't know enough about the workings of dataclasses.dataclass to be > able to say for sure, but a cursory glance does suggest that, in some > way, this should be possible. It may require stringifying the default > though. > > ls: list[int] = "[x, y]" > > ChrisA > _______________________________________________ > Python-ideas mailing list -- python-ideas@python.org > <mailto:python-ideas@python.org> > To unsubscribe send an email to python-ideas-le...@python.org > <mailto:python-ideas-le...@python.org> > https://mail.python.org/mailman3/lists/python-ideas.python.org/ > <https://mail.python.org/mailman3/lists/python-ideas.python.org/> > Message archived at > https://mail.python.org/archives/list/python-ideas@python.org/message/YVLHVQK27TN6M5OKZKXJGUEZX47BRHGK/ > > <https://mail.python.org/archives/list/python-ideas@python.org/message/YVLHVQK27TN6M5OKZKXJGUEZX47BRHGK/> > Code of Conduct: http://python.org/psf/codeofconduct/ > <http://python.org/psf/codeofconduct/> > > > -- > Christopher Barker, PhD (Chris) > > Python Language Consulting > - Teaching > - Scientific Software Development > - Desktop GUI and Web Development > - wxPython, numpy, scipy, Cython > _______________________________________________ > Python-ideas mailing list -- python-ideas@python.org > To unsubscribe send an email to python-ideas-le...@python.org > https://mail.python.org/mailman3/lists/python-ideas.python.org/ > Message archived at > https://mail.python.org/archives/list/python-ideas@python.org/message/KTBG6LBRD5NPKV2JK7BGO7FG34INNP5J/ > Code of Conduct: http://python.org/psf/codeofconduct/
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