{"id":5061,"date":"2025-02-26T20:38:43","date_gmt":"2025-02-27T04:38:43","guid":{"rendered":"https:\/\/wonghoi.humgar.com\/blog\/?p=5061"},"modified":"2025-12-01T02:12:43","modified_gmt":"2025-12-01T10:12:43","slug":"neat-trick-cleaning-up-after-yourself-in-python-the-non-pythonic-the-semi-raii-way-oncleanup","status":"publish","type":"post","link":"https:\/\/wonghoi.humgar.com\/blog\/2025\/02\/26\/neat-trick-cleaning-up-after-yourself-in-python-the-non-pythonic-the-semi-raii-way-oncleanup\/","title":{"rendered":"We use ContextManager (“with … as” statement) in Python because Python’s fundamental language design (garbage collecting objects) broke RAII"},"content":{"rendered":"\n

[TLDR] Python doesn’t have RAII<\/strong>. C++ and MATLAB allows RAII. You can have a proper RAII only if destructor timing is 100% controllable by the programmer.<\/p>\n\n\n\n

Python uses Context Manager<\/a> (with ... as<\/code> idiom) to address the old issue of opening up a resource handler (say a file or network socket) and automatically close (free) it regardless of whether the program quit abruptly or it gracefully terminates after it’s done with the resource.<\/p>\n\n\n\n

Unlike destructors in C++ and MATLAB, which registers what to do (such as closing the resource) when the program quits or right before the resource (object) is gone, Python’s Context Manager is basically rehasing the old try-block idea by creating a rigid framework around it.<\/p>\n\n\n\n

It’s not that Python doesn’t know the RAII mechanism (which is much cleaner), but Python’s fundamental language design choices drove itself to a corner so it’s stuck micro-optimizing the try-except\/catch-finally<\/code> approach of managing opened resourecs:<\/p>\n\n\n\n