|Title:||Make ".canvas lower" work with non-existent belowThis tag|
|Submitter:||stevenaaus||Created on:||2012-07-31 21:54:32|
|Subsystem:||05. Canvas Items||Assigned To:||fvogel|
|Status:||Closed||Last Modified:||2020-02-22 15:39:11|
|Closed on:||2020-02-22 15:39:11|
This is new behaviour, and i ~think~ is probably a bug. If the "belowThis" tag is not defined, wish throws an error. All previous version os wish this does not happen. pack [canvas .c] .c create line 0 0 10 10 -tags aline .c lower aline noline > tag "noline" doesn't match any items
fvogel added on 2020-02-22 15:39:11:
Merged to trunk, following acceptation of the TIP by the TCT.
fvogel added on 2020-02-10 21:45:17: (text/x-fossil-wiki)
I have created [http://core.tcl-lang.org/tips/doc/trunk/tip/565.md|TIP #565] to gather further comments on this.
fvogel added on 2019-12-25 17:00:45: (text/x-fossil-wiki)
I understand what was done in [3437816fff]: symmetry between the error-spitting <code>.canvas raise</code> command and the non-error-spitting <code>.canvas lower</code> was restored so that both spit the same error. Yes this was a bugfix, and the reasons for having done so are explained in that ticket. That said, in the wake of the "Do nothing gracefully" reform, aka [https://core.tcl-lang.org/tips/doc/trunk/tip/323.md|TIP #323], I think we could indeed remove the error when calling <code>.canvas raise|lower</code> with a non-existent "aboveThis"|"belowThis" tag. Especially since the error spitting is currently inconsistent: <verbatim> package require Tk .c create line 0 0 10 10 -tags aline # inconsistent error spitting .c lower aline noline ; # tagOrId "noline" doesn't match any items .c lower bline aline ; # no error # ditto for raise instead of lower: .c raise aline noline ; # tagOrId "noline" doesn't match any items .c raise bline aline ; # no error </verbatim> We would do this in 8.7 and not in 8.6. Would need a small TIP I guess. Comments?
stevenaaus added on 2012-10-28 03:24:12:
The issue is <b>Many</b> tk apps are now going to needlessly start throwing errors. My tkspider game does just this. (screenshot attached). There is no real plus side to this change.
stevenaaus added on 2012-10-28 03:22:18:
File Added - 455554: a6.png
stevenaaus added on 2012-08-01 15:55:13:
I't be nice to not throw an error here (and also modify the raise command's behaviour) * AFAIK - all other references to non-existing tags do not throw errors * This is the way it has been with "lower" for a long time.
dkf added on 2012-08-01 15:50:18:
No, it's a FRQ
dkf added on 2012-08-01 15:48:44:
allow_comments - 0 data_type - 362997
nijtmans added on 2012-08-01 05:08:07:
allow_comments - 1 No, it's a bug fix: See #3437816