New to Python and come from a statically typed language background. I want type hints for https://lxml.de just for ease of development (mypy flagging issues and suggesting methods would be nice!)
To my knowledge, this is a python 2.0 module and doesn’t have types. Currently I’ve used https://mypy.readthedocs.io/en/stable/stubgen.html to create stub type definitions and filling in “any”-types I’m using with more information, but it’s really hacky. Are there any safer ways to get type hints?
There is an official stubs package for lxml now called lxml-stubs:
$ pip install lxml-stubs
Note, however, that the stubs are still in development and are not 100% complete yet (although very much usable from my experience). These stubs were once part of typeshed, then curated by Jelle Zijlstra after removal and now are developed as part of the lxml project.
If you want the development version of the stubs, install via
$ pip install git+https://github.com/lxml/lxml-stubs.git
(the project's readme installation command is missing the git+ prefix in URL's scheme and won't work).
I would not call this "hacky", rather it is gradual typing.
You can take a closer look at lxml-stubs repository. From about:
This repository contains external type annotations (see PEP 484) for the lxml package. Such type annotations are normally included in typeshed, but lxml's annotations were frequently problematic and have therefore been deleted from typeshed. In particular, the stubs are incomplete and it has been difficult to provide complete stubs.
Perhaps it will be useful to you
Recently I have done much more gap filling based on lxml-stubs with some good progress.
Welcome to check out types-lxml if any late comer are still interested. For most people I think lxml.objectify is the only missing piece lacking from the stubs, which is planned immediately after current release.
I’ve used
stubgento create stub type definitions and filling in “any”-types
This is actually the correct approach if it's not lxml; creating template from mypy stubgen is the starting point for many stub files. But lxml is mostly written in Cython, for which stubgen do not have perfect support yet. Besides as OP noted, this is a python 2.0 era module, and author uses function arguments in a quite polymorphous way. There are lots of unique challenges annotating lxml, as lxml is essentially a python interface for libxml and libxslt in its core.
As an example, the support of both unicode and bytes input complicates matter too; this is the same difficulty found when annotating xml.etree bundled with python, but in a much greater magnitude.