Python, type hints, and future annotations

Not long ago, I came across a bug in one of my projects that highlighted very interesting changes in how Python handles type hints at runtime.

This made me dig into the future of type annotations, and what it means for libraries manipulating type hints at runtime. Spoiler alert: It has to do with PEP 563.

• The bug


• 
  A brief history of type hints
  
  
  
  
  • Basics of type hints
  
  
  
  


• Introducing PEP 563, or what lies behind future annotations


• The explanation …

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