25
sys.modules and the truth about import caching
Trace module identity, partial initialization, reloads, and cache invalidation through Python's real import protocol.
Independent field notes / Vol. 01
Python,
below the surface.
Precise explanations of the machinery, patterns, and tradeoffs that make Python feel deceptively simple.
Read the cover storyThe index
Choose a rabbit hole.
29 notes, edited for signal.
26
Tuples, records, and the cost of shape
Immutability, hashing, packing bytecode, shallow memory, and choosing records that communicate their shape.
27
Weak references and caches that can let go
Use weak references, weak containers, and finalizers without confusing reachability, equality, callbacks, or cache policy.
28
How Python dictionaries actually remember
Hashes, collisions, compact entries, and the implementation choices behind Python's most important container.
29
The GIL, without the folklore
What CPython locks, what it does not guarantee, and how free-threaded Python changes the decision.
Editorial policy
No listicles. No folklore. No just trust me abstractions.
Every note should leave you with a better model of the system, not just another snippet to paste.