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{"@context":"https://schema.org","@type":"DiscussionForumPosting","headline":"Isolate the _curses extension module","articleBody":"# Feature or enhancement\r\n\r\nIsolate the `_curses` extension module. This means turning most global variables into module state variables.\r\n\r\nGlobals in the `_curses` extension module:\r\n\r\n| Name | C type | Notes |\r\n| --- | --- | --- |\r\n| PyCursesVersion | const char[] | Hard-coded C string; can remain a global |\r\n| PyCursesError | PyObject \\*  |\r\n| initialised\\_setupterm | int | Tells whether `setupterm()` has been called to initialise `terminfo` |\r\n| initialised | int | Tells whether `initscr()` has been called to initialise curses |\r\n| initialisedcolors | int | Tells whether `start_color()` has been called to initialise color usage |\r\n| screen\\_encoding | int |\r\n| PyCursesWindow_Type | PyTypeObject \\* | Must convert to heap type |\r\n| ModDict | PyObject \\* |\r\n\r\nThere is also a capsule with a C API. I'm not sure if this needs special handling wrt. PEP-489, but the \\_curses C API exposes three of the global variables[^1] directly. That said, those three variables are all guards for curses specific initialisation; it may make sense to keep these variables global; I don't know yet. The capsule C API also uses the \\_curses exception object (`curses.error`). Altering or removing the \\_curses C API is a breaking change and must follow the deprecation cycle of PEP-387.\r\n\r\nApart from the capsule C API issues, converting the remaining global variables to module state variables seem to be an easy task; most of them are used in either module functions or class methods. We can store the state in the `PyCursesWindow_Type` object for easy access and minimal churn.\r\n\r\n# Pitch\r\n\r\nThis is needed in order to support a per-interpreter GIL.\r\n\r\n# Previous discussion\r\n\r\nhttps://github.com/ericsnowcurrently/multi-core-python/wiki/0-The-Plan\r\n\r\n[^1]: `initialised_setupterm`, `initialisedcolors`, and `initialised`\n\n\u003c!-- gh-linked-prs --\u003e\n### Linked PRs\n* gh-104732\n\u003c!-- /gh-linked-prs --\u003e\n","author":{"url":"https://github.com/erlend-aasland","@type":"Person","name":"erlend-aasland"},"datePublished":"2023-02-08T22:42:34.000Z","interactionStatistic":{"@type":"InteractionCounter","interactionType":"https://schema.org/CommentAction","userInteractionCount":8},"url":"https://github.com/101714/cpython/issues/101714"}