pabloem commented on a change in pull request #11943:
URL: https://github.com/apache/beam/pull/11943#discussion_r439075720
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File path: sdks/python/apache_beam/transforms/combiners.py
##########
@@ -66,8 +66,21 @@ class Mean(object):
"""Combiners for computing arithmetic means of elements."""
class Globally(ptransform.PTransform):
"""combiners.Mean.Globally computes the arithmetic mean of the elements."""
+ def __init__(self, has_defaults=True, *args, **kwargs):
+ super(Mean.Globally, self).__init__()
+ self.has_defaults = has_defaults
+ self.args = args
+ self.kwargs = kwargs
+
def expand(self, pcoll):
- return pcoll | core.CombineGlobally(MeanCombineFn())
+ if self.has_defaults:
+ return pcoll | core.CombineGlobally(MeanCombineFn())
+ else:
+ return pcoll | core.CombineGlobally(MeanCombineFn()).without_defaults()
+
+ def without_defaults(self):
+ self.has_defaults = False
Review comment:
what robert means in this case is that rather than mutating and
returning self like so:
```
def without_defaults(self):
self.has_defaults = False
return self
```
It would be more useful to return a new instance with the new property.
Somewhat like this:
```
def with_defaults(self, has_defaults=True):
return Mean.Globally(has_defaults=has_defaults, *self.args, **self.kwargs)
```
It's useful to do this because then instance attributes are immutable, and
it's easier to manage instances with immutable attributes.
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