The Python Podcast.__init__

The Python Podcast.__init__

The podcast about Python and the people who make it great

16 March 2020

Getting A Handle On Portable C Extensions With hpy - E254

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One of the driving factors of Python’s success is the ability for developers to integrate with performant languages such as C and C++. The challenge is that the interface for those extensions is specific to the main implementation of the language. This contributes to difficulties in building alternative runtimes that can support important packages such as NumPy. To address this situation a team of developers are working to create the hpy project, a new interface for extension developers that is standardized and provides a uniform target for multiple runtimes. In this episode Antonio Cuni discusses the motivations for creating hpy, how it benefits the whole ecosystem, and ways to contribute to the effort. This is an exciting development that has the potential to unlock a new wave of innovation in the ways that you can run your Python code.


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  • Your host as usual is Tobias Macey and today I’m interviewing Antonio Cuni about hpy, a project aiming to reimagine the C API for Python


  • Introductions
  • How did you get introduced to Python?
  • Can you start by describing what the hpy project is and how it got started?
    • What are the goals for the project?
    • Who else is involved?
  • How much engagement have you had with CPython core contributors or the steering council?
  • Who are the consumers of the current C API for the CPython implementation?
    • What are some of the pain points or shortcomings for those consumers?
    • What impact does that have for users of a given library that leverages C extensions?
  • Can you talk through the structure of the hpy project?
    • What are some of the design challenges that you are facing for determining the external API?
    • What is involved in integrating the hpy interface into alternate runtimes such as PyPy or RustPython?
  • What is the potential or observed performance impact for libraries that currently rely on the existing C API?
  • How has the vision and scope of this project been updated as you have gotten further along in the implementation?
  • What are the downstream impacts that you anticipate in projects such as PyPy and Cython?
  • What have you found to be the most challenging or contentious aspects of implementing hpy so far?
  • What are some of the most interesting/unexpected/useful lessons that you have learned while working on hpy?
  • What do you have planned for the near to medium term for hpy?

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The intro and outro music is from Requiem for a Fish The Freak Fandango Orchestra / CC BY-SA

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