match val:
case [*str()]:
...
Where 'val' will match an iterable containing zero or more strings.
This should also work with more complex sub-patterns, like:
match humans:
case [
*{
'name': str(),
'age': int(),
}
]:
...
Where 'humans' should match an iterable of zero or more mappings where each
mapping
contains the keys 'name' and 'age' (and where the value for name is a string and the value for age is an int).
I haven't yet used pattern matching, but even without that context, this strikes me as mathicn on type, rather than value.
which doesn't, in my mind, belong in code that's going to run during run time.
I wouldn't write:
if obj and all( isinstance(o, str) for o in obj):
do_something
so why would I use it in pattern matching?
Granted, the distinction between type and value gets a bit messy in Python, but I"d think:
each
mapping
contains the keys 'name' and 'age'
would be value, but:
(and where the value for name is a string and the value for age is an int).
would be type.
I do see that kind of checking to be useful, for, e.g. unpacking JSON data, but I'm not sure this is where it belongs -- that kind of checking, to me, is validation of the JSON, defining the structure belongs in a different place, in a different way.
I would be interested in hearing about the use cases you have in mind, and where that fits into the whole type vs value checking continuum.
-CHB
--
Christopher Barker, PhD (Chris)
Python Language Consulting
- Teaching
- Scientific Software Development
- Desktop GUI and Web Development
- wxPython, numpy, scipy, Cython