René's URL Explorer Experiment

{"@context":"https://schema.org","@type":"DiscussionForumPosting","headline":"[MNT]: Deprecate `onselect`/`onmove_callback` of selectors","articleBody":"### Summary\n\nIf I remember correctly, at some point, @anntzer suggested to deprecate `onselect` argument for selectors. Now, that I understand better what he meant at the time, I think it makes a lot of sense, because the behaviour of the \"builtin\" selector callback is contentious and inconsistent between selectors.\r\n\n\n### Proposed fix\n\n\r\nThe alternative would be something along the lines of:\r\n```python\r\nimport matplotlib.pyplot as plt\r\nfrom matplotlib.widgets import RectangleSelector\r\nimport functools\r\n\r\n_, ax = plt.subplots()\r\nax.plot([1, 2, 3])\r\n\r\n\r\ndef dummy_callback(*args):\r\n    pass\r\n\r\n\r\ndef onselect_callback(event, selector):\r\n    print('## onselect callback ##')\r\n    if not selector.ignore(event):\r\n        print('   ', selector.extents)\r\n        return\r\n    print('   event ignored')\r\n\r\n\r\ndef onmove_callback(event, selector):\r\n    print('## onmove callback ##')\r\n    if not selector.ignore(event) and selector._eventpress:\r\n        print('   ', selector.extents)\r\n        return\r\n    print('   event ignored')\r\n\r\n\r\ntool = RectangleSelector(ax, dummy_callback, interactive=True,\r\n                         drag_from_anywhere=True,)\r\ntool.extents = (1.2, 2.0, 1.0, 1.6)\r\n\r\n# alternative to onselect\r\nrectangle_onselect_callback = functools.partial(onselect_callback, selector=tool)\r\ntool.connect_event('button_release_event', rectangle_onselect_callback)\r\n\r\n# alternative to onmove_callback (SpanSelector only)\r\nrectangle_onmove_callback = functools.partial(onmove_callback, selector=tool)\r\ntool.connect_event('motion_notify_event', rectangle_onmove_callback)\r\n\r\n```\r\n\r\nIn my opinion, the reasons to deprecate are:\r\n- provide consistent API between selectors\r\n- leave the user define what is the expected behaviour - anyway, I don't think the current API is obvious to use\r\n- fix https://github.com/matplotlib/matplotlib/issues/9608 (see #20611 for more discussion)\r\n- simplify maintenance\r\n\r\nProposed fix:\r\n- Deprecate the `onselect`/`onmove` arguments of the selectors, as per example above\r\n- improve the API to ignore events (the example above uses a private API to reproduce the `onmove_callback` of the `SpanSelector`)\r\n- update example, improve documentation on the use of callback registry.","author":{"url":"https://github.com/ericpre","@type":"Person","name":"ericpre"},"datePublished":"2021-12-11T12:49:58.000Z","interactionStatistic":{"@type":"InteractionCounter","interactionType":"https://schema.org/CommentAction","userInteractionCount":5},"url":"https://github.com/21929/matplotlib/issues/21929"}