Replace all uses of Query::single with Single
#15866
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A-Cross-Cutting
Impacts the entire engine
C-Code-Quality
A section of code that is hard to understand or change
C-Examples
An addition or correction to our examples
D-Trivial
Nice and easy! A great choice to get started with Bevy
S-Ready-For-Implementation
This issue is ready for an implementation PR. Go for it!
X-Uncontroversial
This work is generally agreed upon
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alice-i-cecile
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I opened TheBevyFlock/bevy_cli#136, which would make the |
from @pablo-lua in https://discord.com/channels/691052431525675048/749335865876021248/1294672821687025707
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# Objective - closes #15866 ## Solution - Simply migrate where possible. ## Testing - Expect that CI will do most of the work. Examples is another way of testing this, as most of the work is in that area. --- ## Notes For now, this PR doesn't migrate `QueryState::single` and friends as for now, this look like another issue. So for example, QueryBuilders that used single or `World::query` that used single wasn't migrated. If there is a easy way to migrate those, please let me know. Most of the uses of `Query::single` were removed, the only other uses that I found was related to tests of said methods, so will probably be removed when we remove `Query::single`.
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What problem does this solve or what need does it fill?
Query::singleandQuery::single_mutare convenient lazy helpers with a nasty side effect: they panic unless exactly one matching entity is found!While this is fine, in theory, for polished, tiny example code, it teaches bad habits to our users.
What solution would you like?
We should swap over all panicking uses over to the shiny new
Singlesystem param.In rare cases, swapping to
Query::get_singleor evenOption<Single<&Component>>might be preferred, to allow for more detailed error handling or to ensure the system runs to do secondary work even if the single entity it's looking for isn't found.What alternative(s) have you considered?
We could remove these methods entirely, per #14275. This is a much larger and more controversial change. Even if this is chosen, this migration needs to be done anyways, so we might as well do it now.
Additional context
The nascent
bevy_cliproject introduced a lint to check for this class of error: TheBevyFlock/bevy_cli#95. At some point, we'll want to run that Bevy-specific linter in CI for this project, but it's not ready yet.The text was updated successfully, but these errors were encountered: