zero323 commented on a change in pull request #34363:
URL: https://github.com/apache/spark/pull/34363#discussion_r760208707
##########
File path: python/pyspark/accumulators.py
##########
@@ -176,44 +193,44 @@ class AccumulatorParam(object):
[7.0, 8.0, 9.0]
"""
- def zero(self, value):
+ def zero(self, value: T) -> T:
"""
Provide a "zero value" for the type, compatible in dimensions with the
provided `value` (e.g., a zero vector)
"""
raise NotImplementedError
- def addInPlace(self, value1, value2):
+ def addInPlace(self, value1: T, value2: T) -> T:
"""
Add two values of the accumulator's data type, returning a new value;
for efficiency, can also update `value1` in place and return it.
"""
raise NotImplementedError
-class AddingAccumulatorParam(AccumulatorParam):
+class AddingAccumulatorParam(AccumulatorParam[U]):
"""
An AccumulatorParam that uses the + operators to add values. Designed for
simple types
such as integers, floats, and lists. Requires the zero value for the
underlying type
as a parameter.
"""
- def __init__(self, zero_value):
+ def __init__(self, zero_value: U):
self.zero_value = zero_value
- def zero(self, value):
+ def zero(self, value: U) -> U:
return self.zero_value
- def addInPlace(self, value1, value2):
+ def addInPlace(self, value1: U, value2: U) -> U:
value1 += value2
Review comment:
OK, so reducing this a bit:
```python
# main.py
from __future__ import annotations
from typing import Generic, Protocol, TypeVar
T = TypeVar("T")
U = TypeVar("U", bound=SupportsIAdd)
class SupportsIAdd(Protocol):
def __iadd__(self: T, other: T) -> T: ...
class AddingAccumulatorParam(Generic[U]):
def addInPlace(self, value1: U, value2: U) -> U:
value1 += value2
return value1
```
```
main.py:17: error: Unsupported left operand type for + ("U")
Found 1 error in 1 file (checked 1 source file)
```
but after replacing `__iadd__` with `__add__` passes
```python
# main.py
from __future__ import annotations
from typing import Generic, Protocol, TypeVar
T = TypeVar("T")
U = TypeVar("U", bound=SupportsIAdd)
class SupportsIAdd(Protocol):
def __add__(self: T, other: T) -> T: ...
class AddingAccumulatorParam(Generic[U]):
def addInPlace(self, value1: U, value2: U) -> U:
value1 += value2
return value1
```
I honestly don't see why, but there are all kinds of subtleties around
`__iadd__`, `__radd__` and `__add__`. Anyone?
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