chadrik commented on a change in pull request #11070: URL: https://github.com/apache/beam/pull/11070#discussion_r426054969
########## File path: website/src/_posts/2020-03-06-python-typing.md ########## @@ -0,0 +1,117 @@ +--- +layout: post +title: "Python SDK Typing Changes" +date: 2020-03-06 00:00:01 -0800 +excerpt_separator: <!--more--> +categories: blog python typing +authors: + - chadrik + - udim + +--- +<!-- +Licensed under the Apache License, Version 2.0 (the "License"); +you may not use this file except in compliance with the License. +You may obtain a copy of the License at + +http://www.apache.org/licenses/LICENSE-2.0 + +Unless required by applicable law or agreed to in writing, software +distributed under the License is distributed on an "AS IS" BASIS, +WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. +See the License for the specific language governing permissions and +limitations under the License. +--> + +TODO excerpt + +<!--more--> + +Python supports type annotations on functions (PEP 484). Static type checkers, +such as mypy, are used to verify adherence to these types. +For example: +```py +def f(v: int) -> int: + return v[0] +``` +Running mypy on the above code will give the error: +`Value of type "int" is not indexable`. + +We've recently made changes to Beam in 2 areas: + +Adding type hints throughout Beam. TODO expand + +Second, we've added support for Python 3 type annotations. This allows SDK +users to specify a DoFn's type hints in one place. +We've also expanded Beam's support of `typing` module types. + +For more background see: +[Ensuring Python Type Safety](https://beam.apache.org/documentation/sdks/python-type-safety/). + +# Beam Is Typed + +TODO Review comment: ```suggestion In tandem with the new type annotation support within DoFns, we've invested a great deal of time adding type annotations to the Beam python code itself. With this in place, we have begun using mypy, a static type checker, as part of Beam's code review process, which ensures higher quality contributions and fewer bugs. The added context and insight that type annotations add throughout Beam is useful for all Beam developers, contributors and end users alike, but it is especially beneficial for developers who are new to the project. If you use an IDE that understands type annotations, it will provide richer type completions and warnings than before. You'll also be able to use your IDE to inspect the types of Beam functions and transforms to better understand how they work, which will ease your own development. Finally, once Beam is fully annotated, end users will be able to benefit from the use of static type analysis on their own pipelines and custom transforms. ``` ---------------------------------------------------------------- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. For queries about this service, please contact Infrastructure at: us...@infra.apache.org
