On 2017-12-21 22:45, Chris Barker wrote:
On Thu, Dec 21, 2017 at 11:55 AM, Terry Reedy <tjre...@udel.edu
<mailto:tjre...@udel.edu>> wrote:
I think the understanding problem with this feature arises from two
factors: using annotations to define possibly un-initialized slots
is non-obvious; a new use of annotations for something other than
static typing is a bit of a reversal of the recent pronouncement
'annotations should only be used for static typing'.
you know, that may be where part of my confusion came from -- all the
talk lately has been about "type hints" and "type annotations" -- the
idea of "arbitrary annotations" has been lost.
Therefore, getting the permanent doc 'right' is important.
yup.
@dataclass
class C:
x
y = 0
I think the doc should explicitly say that uninitialized fields
require annotation with something (anything, not necessarily a type)
simply to avoid NameError during class creation.
would this be possible?
@dataclass
class C:
x:
y: = 0
That is -- the colon indicates an annotation, but in this case, it's a
"nothing" annotation.
"..." or "pass", perhaps?
@dataclass
class C:
x: ...
y: ... = 0
or:
@dataclass
class C:
x: pass
y: pass = 0
It's a syntax error now, but would it be possible to change that? Or
would the parsing be ambiguous? particularly in other contexts.
of course, then we'd need something to store in as a "nothing"
annotation -- empty string? None? (but None might mean something) create
yet anther type for "nothing_annotation"
Hmm, I may have talked myself out of it....
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