Re: [PATCH v9 08/14] iotests: touch up log function signature

[Max Reitz <mreitz@redhat.com>]

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On 25.03.20 00:20, John Snow wrote:
> Representing nested, recursive data structures in mypy is notoriously
> difficult; the best we can reliably do right now is denote the atom
> types as "Any" while describing the general shape of the data.
> 
> Regardless, this fully annotates the log() function.
> 
> Typing notes:
> 
> TypeVar is a Type variable that can optionally be constrained by a
> sequence of possible types. This variable is bound per-invocation such
> that the signature for filter=() requires that its callables take e.g. a
> str and return a str.

So it works like a generic, except that its declaration isn’t part of
and thus local to the function.  Interesting.  Not sure if I like it,
but, well, it’s Python.  (Seems to me on the same level of “Interesting”
as the “Don’t use an empty list as a default argument” thing.[1])

> Signed-off-by: John Snow <jsnow@redhat.com>
> ---
>  tests/qemu-iotests/iotests.py | 14 +++++++++++---
>  1 file changed, 11 insertions(+), 3 deletions(-)

Haha.  I can’t help but find it funny how my “I won’t complain, but I
feel like some people might want this to be two patches” led to this “If
I’m going to make a dedicated patch for this, I might as well go all the
way” patch.  It’s quite cool.

Reviewed-by: Max Reitz <mreitz@redhat.com>

[1] I just read an article on that thing again (empty lists as default
argument), which claims that this is in fact a very useful feature of
Python.  This makes me want to go on another rant, but I’ve learned
enough restraint by now not to.


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