On Sat, Oct 9, 2021 at 10:02 AM Jeremiah Paige <ucod...@gmail.com> wrote: > > On Fri, Oct 8, 2021 at 2:30 PM Chris Angelico <ros...@gmail.com> wrote: >> >> On Sat, Oct 9, 2021 at 6:24 AM Jeremiah Paige <ucod...@gmail.com> wrote: >> > Bellow are some examples of where I believe the reflection token would be >> > used if adopted. >> > >> > >> > >>> Point = namedtuple(<<<, 'x, y, z') >> > >>> Point >> > <class '__main__.Point'> >> > >> > >> > >>> UUIDType = NewType(<<<, str) >> > >>> UUIDType >> > __main__.UUIDType >> >> Not very commonly needed. The class keyword handles this just fine; >> namedtuple does require that repetition, but I don't know of any other >> cases where people construct types like this. > > > Besides these two and the two more in the test file, the standard > library has type, new_class, import_module, TypedDict, ParamSpec, > and probably more, less used, factories I have missed.
But most of those don't need to be used with constants. You don't use the type constructor when you could just use a class statement. I'm not sure about the others since I have literally never used them in production; which is an indication of how much they need special syntax to support them (namely: approximately zero). >> > >>> class Colors(Enum): >> > ... Black = <<< >> > ... GRAY = <<< >> > ... WHITE = <<< >> > ... >> > >>> Colors.GRAY.value >> > 'GRAY' >> >> Can do this just as easily using Enum.auto(). > > > That's fair, but this works for constants in dataclasses, attrs, generally > any class or namespace. Can you provide better examples then? When you offer a new piece of syntax, saying "well, it could be useful for other things" isn't nearly as convincing as actual examples that will make people's lives better. >> > >>> HOME = '$' + <<< >> > >>> HOME >> > '$HOME' >> >> Wow, this is so incredibly useful. I'm sure I would use this construct >> *at least* once per decade if it existed. > > > Perhaps the concatenation, showing it is just a string, was a poor > example. In my own code I often make strings that are reused, such as > for dict key access, variables of the same spelling. It looks like cpython > also does this at least a few hundred times. Again, need better examples if it's to be of value. Preferably, show places where it's not just a matter of saving keystrokes (which are cheap) - show places where it reduces errors. > The syntax is not only helpful to dictionary unpacking, but any retrieval by > string and so is general to e.g. match.group, list.index, Message.get. Match groups (assuming they're named - personally, I more often use positional groups) and Message.get are definitely a plausible use-case for something, but this syntax isn't really selling it. I've no idea what your use-cases for list.index are. A generic unpacking syntax might be plausible, but it would need to handle multiple unpackings in a single operation, and it'd achieve something like: spam, ham, eggs, sausages = foo["spam"], foo["ham"], foo["eggs"], foo["sausages"] Writing that in a way that doesn't involve repeating the keys OR the thing being unpacked *would* be tempting, but the syntax you're proposing can't handle that. If your use-cases are like this, I would be much more inclined to recommend class syntax, maybe with a suitable decorator. It's a great way to create a namespace. You can do all kinds of namespace-like things by starting with a declarative structure and then giving that to whatever function you like. ChrisA _______________________________________________ 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/QADKWE5MIVB43CZTRULRNLSFTRF4FFIM/ Code of Conduct: http://python.org/psf/codeofconduct/
