[Python-Dev] PyOS_InputHook enhancement proposal (original) (raw)

Michiel Jan Laurens de Hoon mdehoon at ims.u-tokyo.ac.jp
Thu Dec 9 05:47:01 CET 2004

PyOS_InputHook is a pointer to a function that is called periodically (ten times per second) while Python is idle, for example, when waiting for a user command. Python C extension modules can set this pointer to a hook function defined in the extension module. For example, _tkinter.c makes use of PyOS_InputHook to get messages delivered to its widgets.

A problem arises when two or more extension modules want to set PyOS_InputHook. For example, the scientific plotting package pygist needs PyOS_InputHook to get messages delivered to its graphics windows, and may therefore conflict with the Python GUI IDLE, which uses Tkinter. Chaining won't work, as it will fail when an extension module wants to remove its hook function.

My suggestion is therefore to replace PyOS_InputHook by two functions PyOS_AddInputHook and PyOS_RemoveInputHook, and let Python keep track of which hooks are installed. This way, an extension module can add a hook function without having to worry about other extension modules trying to use the same hook.

Any comments? Would I need to submit a PEP for this proposal?

--Michiel, U Tokyo.

-- Michiel de Hoon, Assistant Professor University of Tokyo, Institute of Medical Science Human Genome Center 4-6-1 Shirokane-dai, Minato-ku Tokyo 108-8639 Japan http://bonsai.ims.u-tokyo.ac.jp/~mdehoon

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