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https://issues.apache.org/jira/browse/BEAM-7746?focusedWorklogId=393852&page=com.atlassian.jira.plugin.system.issuetabpanels:worklog-tabpanel#worklog-393852
]
ASF GitHub Bot logged work on BEAM-7746:
----------------------------------------
Author: ASF GitHub Bot
Created on: 26/Feb/20 23:48
Start Date: 26/Feb/20 23:48
Worklog Time Spent: 10m
Work Description: chadrik commented on pull request #10822: [BEAM-7746]
Minor typing updates / fixes
URL: https://github.com/apache/beam/pull/10822#discussion_r384836306
##########
File path: sdks/python/apache_beam/transforms/external_java.py
##########
@@ -37,18 +39,19 @@
# Protect against environments where apitools library is not available.
# pylint: disable=wrong-import-order, wrong-import-position
+apiclient = None # type: Optional[types.ModuleType]
Review comment:
I did some more research on this, and I found this mypy issue:
https://github.com/python/mypy/issues/1297
It suggests this idiom:
```python
try:
from apache_beam.runners.dataflow.internal import apiclient as _apiclient
except ImportError:
apiclient = None
else:
apiclient = _apiclient
```
The import is a bit longer and uglier, but it has 2 advantages:
- no need to import `Optional` or `ModuleType`
- the idiom I was using was actually making `apiclient` a generic
ModuleType, dropping all knowledge of the members of
`apache_beam.runners.dataflow.internal`. That's bad!
The reason this works without explicit `Optional` annotation that mypy will
automatically determine optionality in some cases, like this:
```python
if some_conditional():
x = None
else:
x = 1
reveal_type(x) # Revealed type is 'Union[builtins.int, None]'
```
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Issue Time Tracking
-------------------
Worklog Id: (was: 393852)
Time Spent: 67h 20m (was: 67h 10m)
> Add type hints to python code
> -----------------------------
>
> Key: BEAM-7746
> URL: https://issues.apache.org/jira/browse/BEAM-7746
> Project: Beam
> Issue Type: New Feature
> Components: sdk-py-core
> Reporter: Chad Dombrova
> Assignee: Chad Dombrova
> Priority: Major
> Time Spent: 67h 20m
> Remaining Estimate: 0h
>
> As a developer of the beam source code, I would like the code to use pep484
> type hints so that I can clearly see what types are required, get completion
> in my IDE, and enforce code correctness via a static analyzer like mypy.
> This may be considered a precursor to BEAM-7060
> Work has been started here: [https://github.com/apache/beam/pull/9056]
>
>
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