[BEAM-524] Description of "type" argument in Aggregator is incorrect

• Type: Bug
• Status: Resolved
• Priority: P3
• Resolution: Fixed
• Fix Version/s: Not applicable
• Component/s: sdk-py-core
• Assignee: Unassigned
• Reporter: Frank Yellin
• Created: 03/Aug/16 23:49
• Updated: 16/May/20 13:21
• Resolved: 04/Apr/17 04:23

Description

Two problems with documentation for "type" argument.

Trivial: Remove "by default". This phrase implies that there are other alternatives besides what is listed. There aren't.

Non trivial. The documentation says "types appropriate to the combine_fn" are accepted. I tried
Accumulator("foo", max, datetime.datetime)
This failed even though "datetime.datetime" is a perfectly reasonable type to want to take the max of. (I wanted to know precisely when the last job finished.)

Either the documentation needs to be changed to specify that max/min only apply to numeric types, or the code needs to be changed to allow other uses of min and max.

I suspect that the other operators also suffer similar limitations. I doubt that I'd be allowed to sum numpy arrays, even though they support +.