On 1 Jul 2020, at 17:58, Guido van Rossum wrote:
If you are interested in learning more about how PEP 622 would work in
practice, but don't feel like compiling a Python 3.10 fork from
source,
here's good news for you.
In a hurry?
https://mybinder.org/v2/gh/gvanrossum/patma/master?urlpath=lab/tree/playground-622.ipynb
If I change the example code to:
---------------------------------------------------
from dataclasses import dataclass
@dataclass
class Point:
x: int
y: int
z = 42
def whereis(point):
w = 23
match point:
case Point(0, 0):
print("Origin")
case Point(0, y):
print(f"Y={y}")
case Point(x, 0):
print(f"X={x}")
case Point():
print("Somewhere else")
case .w:
print("Not the answer")
case .z:
print("The answer")
case z:
print("Not a point")
---------------------------------------------------
whereis(42)
gives me:
---------------------------------------------------
UnboundLocalError Traceback (most recent call
last)
<ipython-input-16-3257cdeaff94> in <module>
----> 1 whereis(42)
<ipython-input-13-35ff7b1c0f2f> in whereis(point)
10 def whereis(point):
11 w = 23
12 match point:
13 case Point(0, 0):
14 print("Origin")
15 case Point(0, y):
16 print(f"Y={y}")
17 case Point(x, 0):
18 print(f"X={x}")
19 case Point():
20 print("Somewhere else")
21 case .w:
22 print("Not the answer")
---> 23 case .z:
24 print("The answer")
25 case z:
26 print("Not a point")
UnboundLocalError: local variable 'z' referenced before assignment
---------------------------------------------------
This looks strange to me. In all other cases of variable lookup the
global variable z would be found.
whereis(23) however works.
[...]
Servus,
Walter
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