{"action":"created","issue":{"url":"https://api.github.com/repos/matplotlib/matplotlib/issues/5111","labels_url":"https://api.github.com/repos/matplotlib/matplotlib/issues/5111/labels{/name}","comments_url":"https://api.github.com/repos/matplotlib/matplotlib/issues/5111/comments","events_url":"https://api.github.com/repos/matplotlib/matplotlib/issues/5111/events","html_url":"https://github.com/matplotlib/matplotlib/issues/5111","id":107537329,"number":5111,"title":"nbagg backend captures exceptions raised by callbacks","user":{"login":"ngoldbaum","id":3126246,"avatar_url":"https://avatars.githubusercontent.com/u/3126246?v=3","gravatar_id":"","url":"https://api.github.com/users/ngoldbaum","html_url":"https://github.com/ngoldbaum","followers_url":"https://api.github.com/users/ngoldbaum/followers","following_url":"https://api.github.com/users/ngoldbaum/following{/other_user}","gists_url":"https://api.github.com/users/ngoldbaum/gists{/gist_id}","starred_url":"https://api.github.com/users/ngoldbaum/starred{/owner}{/repo}","subscriptions_url":"https://api.github.com/users/ngoldbaum/subscriptions","organizations_url":"https://api.github.com/users/ngoldbaum/orgs","repos_url":"https://api.github.com/users/ngoldbaum/repos","events_url":"https://api.github.com/users/ngoldbaum/events{/privacy}","received_events_url":"https://api.github.com/users/ngoldbaum/received_events","type":"User","site_admin":false},"labels":[{"url":"https://api.github.com/repos/matplotlib/matplotlib/labels/GUI/nbagg","name":"GUI/nbagg","color":"d4c5f9"}],"state":"open","locked":false,"assignee":null,"milestone":{"url":"https://api.github.com/repos/matplotlib/matplotlib/milestones/12","html_url":"https://github.com/matplotlib/matplotlib/milestones/proposed%20next%20point%20release%20(2.1)","labels_url":"https://api.github.com/repos/matplotlib/matplotlib/milestones/12/labels","id":534144,"number":12,"title":"proposed next point release (2.1)","description":"Next feature release.\r\n\r\nBig ticket items:\r\n\r\n - MEP 22/27\r\n - traitlets","creator":{"login":"tacaswell","id":199813,"avatar_url":"https://avatars.githubusercontent.com/u/199813?v=3","gravatar_id":"","url":"https://api.github.com/users/tacaswell","html_url":"https://github.com/tacaswell","followers_url":"https://api.github.com/users/tacaswell/followers","following_url":"https://api.github.com/users/tacaswell/following{/other_user}","gists_url":"https://api.github.com/users/tacaswell/gists{/gist_id}","starred_url":"https://api.github.com/users/tacaswell/starred{/owner}{/repo}","subscriptions_url":"https://api.github.com/users/tacaswell/subscriptions","organizations_url":"https://api.github.com/users/tacaswell/orgs","repos_url":"https://api.github.com/users/tacaswell/repos","events_url":"https://api.github.com/users/tacaswell/events{/privacy}","received_events_url":"https://api.github.com/users/tacaswell/received_events","type":"User","site_admin":false},"open_issues":406,"closed_issues":238,"state":"open","created_at":"2014-01-13T03:21:09Z","updated_at":"2015-09-21T15:53:03Z","due_on":null,"closed_at":null},"comments":4,"created_at":"2015-09-21T15:28:34Z","updated_at":"2015-09-21T17:36:06Z","closed_at":null,"body":"This is illustrated by this notebook:\r\n\r\nhttps://gist.github.com/anonymous/e6cb1acd8bfbfda35bf1\r\n\r\nThe code in the notebook is adapted from [an example](http://matplotlib.org/examples/event_handling/viewlims.html) in the matplotlib docs. I've modified the example so that the `ax_update` function simply raises an error instead of doing anything useful. This is supposed to represent a buggy callback function that raises an exception.\r\n\r\nUsing the nbagg backend, if I run the notebook and then zoom in somewhere on the right-hand axis, I do not get a traceback printed in the notebook despite the fact that `ax_update` is being called and raising an exception.\r\n\r\nUsing the macosx backend doing the exact same thing does print out a traceback after manipulating the right-hand axes in the GUI window.\r\n\r\nNot getting information about errors raised by callback functions makes it very difficult to debug callbacks using the nbagg backend. It would be much better if errors were raised to the level of the user."},"comment":{"url":"https://api.github.com/repos/matplotlib/matplotlib/issues/comments/142052705","html_url":"https://github.com/matplotlib/matplotlib/issues/5111#issuecomment-142052705","issue_url":"https://api.github.com/repos/matplotlib/matplotlib/issues/5111","id":142052705,"user":{"login":"OceanWolf","id":3758703,"avatar_url":"https://avatars.githubusercontent.com/u/3758703?v=3","gravatar_id":"","url":"https://api.github.com/users/OceanWolf","html_url":"https://github.com/OceanWolf","followers_url":"https://api.github.com/users/OceanWolf/followers","following_url":"https://api.github.com/users/OceanWolf/following{/other_user}","gists_url":"https://api.github.com/users/OceanWolf/gists{/gist_id}","starred_url":"https://api.github.com/users/OceanWolf/starred{/owner}{/repo}","subscriptions_url":"https://api.github.com/users/OceanWolf/subscriptions","organizations_url":"https://api.github.com/users/OceanWolf/orgs","repos_url":"https://api.github.com/users/OceanWolf/repos","events_url":"https://api.github.com/users/OceanWolf/events{/privacy}","received_events_url":"https://api.github.com/users/OceanWolf/received_events","type":"User","site_admin":false},"created_at":"2015-09-21T17:36:06Z","updated_at":"2015-09-21T17:36:06Z","body":"You mean akin to the widgetisaton I did for ``WebAgg`` in the MEP27 branch?"}}