If Python is Interpreted, What are .pyc Files and Why Do They Exist?

If Python is an Interpreted Language, What are .pyc Files?

Python is commonly known as an interpreted language. However, many users are perplexed by the presence of .pyc files in their source directories, which are labeled as "Compiled Python Files" by Windows.

To understand this apparent contradiction, it's essential to clarify the distinction between a language and its implementation. Similar to how "The Bible" refers to a class of books with fundamental commonalities, "Python" represents a class of language implementations that adhere to certain core principles.

Like physical Bibles, different implementations of Python can vary in their specifics, including how they handle source files. CPython, the most prevalent Python implementation, follows a strategy known as dynamic compilation.

Dynamic compilation involves translating Python source code into an intermediate form called bytecode. When a Python script is run, CPython automatically checks if a corresponding bytecode file exists. If not, or if the bytecode file is outdated, the compiler quickly and transparently translates the source into bytecode.

The generated bytecode is then executed by the CPython virtual machine. This approach combines the performance benefits of compiled code with the flexibility and ease of use of an interpreted language.

So, while Python is an interpreted language in the sense that its source code is not directly converted to machine code, it does utilize a lightweight compilation step to enhance execution speed. The .pyc files observed in source directories are simply the bytecode files generated by CPython to expedite future execution of the Python script.

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