> there are no known examples of binary matrix multiplication results which may
> used as decorators.
This is misleading. There are multiple libraries on PyPI that wrap up functions
to add additional operators and methods including @ for compose. (It’s also
been proposed and rejected repeatedly for the builtin type, going back to the
rejected PEPs in 2000 that originally proposed a matmul operator.) And
composing two decorators isn’t binary matrix multiplication, but it is a use of
the @ operator; and it gives you results which could be used as decorators.
For example, if I have a logcall decorator that wraps its function with calls
to logging.log that show when the function is entered and exited, and a daytime
decorator that skips the function call if it’s nighttime, then logcall@daytime
is a decorator which skips the function call if it’s nighttime but always logs
either way, while daytime@logcall skips both.
I don’t think that this is a practical problem. I don’t know how often people
use these libraries to compose decorators, but even if it’s very frequent
(which it probably isn’t), it wouldn’t look at all ambiguous to a human to mix
with this feature, because the following end up meaning the same thing:
@daytime@logcall
def cheese(…):
@daytime
@logcall
def cheese(…):
Try it with composing decorators that take arguments and return the actual
decorator, etc.; it’s never ambiguous or misleading to the reader.
So, I think the PEP can dismiss the problem, just not in the way it currently
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