fix(deepMap): incorrect previous value when listening deep store #290
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Thanks. Released in 0.10.3. |
russelldavis
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May 16, 2024
Previously, calling setKey on a $deepMap would mutate the value in-place. This can cause various problems, for example nanostores#250 and nanostores#290. Those were both solved with workarounds, however, this solves it in a better way, by not mutating the deepMap in the first place. Some advantages of this approach: * No need for structuredClone * The oldValue passed to listeners is the same object reference as the value that was previously passed. This is how immutable stores usually work, so it will align better with expectations, cause fewer issues, and allow for new use cases, like the upcoming batching PR which needs that. * Copies were already being made at each nesting level of the key being set, they just weren't being used (so maybe this was the original intent?). Either way, that means there's no new work being done, and perf will actually improve since we no longer need to call structuredClone on oldValue. As part of this change, when a key path extends past the end of an array the result will be a sparse array rather than filling it with undefined. It would have required extra code (and slower perf) to keep the old behavior, and I don't see a good reason for it. The new behavior aligns with what JS does natively, and with other stores like SolidJS. But let me know if that's a problem.
russelldavis
added a commit
to russelldavis/nanostores
that referenced
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May 16, 2024
Previously, calling setKey on a $deepMap would mutate the value in-place. This can cause various problems, for example nanostores#250 and nanostores#290. Those were both solved with workarounds, however, this solves it in a better way, by not mutating the deepMap in the first place. Some advantages of this approach: * No need for structuredClone * The oldValue passed to listeners is the same object reference as the value that was previously passed. This is how immutable stores usually work, so it will align better with expectations, cause fewer issues, and allow for new use cases, like the upcoming batching PR which needs that. * Copies were already being made at each nesting level of the key being set, they just weren't being used (so maybe this was the original intent?). Either way, that means there's no new work being done, and perf will actually improve since we no longer need to call structuredClone on oldValue. As part of this change, when a key path extends past the end of an array the result will be a sparse array rather than filling it with undefined. It would have required extra code (and slower perf) to keep the old behavior, and I don't see a good reason for it. The new behavior aligns with what JS does natively, and with other stores like SolidJS. But let me know if that's a problem.
russelldavis
added a commit
to russelldavis/nanostores
that referenced
this pull request
May 16, 2024
Previously, calling setKey on a $deepMap would mutate the value in-place. This can cause various problems, for example nanostores#250 and nanostores#290. Those were both solved with workarounds, however, this solves it in a better way, by not mutating the deepMap in the first place. Some advantages of this approach: * No need for structuredClone * The oldValue passed to listeners is the same object reference as the value that was previously passed. This is how immutable stores usually work, so it will align better with expectations, cause fewer issues, and allow for new use cases, like the upcoming batching PR which needs that. * Copies were already being made at each nesting level of the key being set, they just weren't being used (so maybe this was the original intent?). Either way, that means there's no new work being done, and perf will actually improve since we no longer need to call structuredClone on oldValue. As part of this change, when a key path extends past the end of an array the result will be a sparse array rather than filling it with undefined. It would have required extra code (and slower perf) to keep the old behavior, and I don't see a good reason for it. The new behavior aligns with what JS does natively, and with other stores like SolidJS. But let me know if that's a problem.
ai
pushed a commit
that referenced
this pull request
May 16, 2024
Previously, calling setKey on a $deepMap would mutate the value in-place. This can cause various problems, for example #250 and #290. Those were both solved with workarounds, however, this solves it in a better way, by not mutating the deepMap in the first place. Some advantages of this approach: * No need for structuredClone * The oldValue passed to listeners is the same object reference as the value that was previously passed. This is how immutable stores usually work, so it will align better with expectations, cause fewer issues, and allow for new use cases, like the upcoming batching PR which needs that. * Copies were already being made at each nesting level of the key being set, they just weren't being used (so maybe this was the original intent?). Either way, that means there's no new work being done, and perf will actually improve since we no longer need to call structuredClone on oldValue. As part of this change, when a key path extends past the end of an array the result will be a sparse array rather than filling it with undefined. It would have required extra code (and slower perf) to keep the old behavior, and I don't see a good reason for it. The new behavior aligns with what JS does natively, and with other stores like SolidJS. But let me know if that's a problem.
ai
pushed a commit
that referenced
this pull request
Jun 25, 2024
Previously, calling setKey on a $deepMap would mutate the value in-place. This can cause various problems, for example #250 and #290. Those were both solved with workarounds, however, this solves it in a better way, by not mutating the deepMap in the first place. Some advantages of this approach: * No need for structuredClone * The oldValue passed to listeners is the same object reference as the value that was previously passed. This is how immutable stores usually work, so it will align better with expectations, cause fewer issues, and allow for new use cases, like the upcoming batching PR which needs that. * Copies were already being made at each nesting level of the key being set, they just weren't being used (so maybe this was the original intent?). Either way, that means there's no new work being done, and perf will actually improve since we no longer need to call structuredClone on oldValue. As part of this change, when a key path extends past the end of an array the result will be a sparse array rather than filling it with undefined. It would have required extra code (and slower perf) to keep the old behavior, and I don't see a good reason for it. The new behavior aligns with what JS does natively, and with other stores like SolidJS. But let me know if that's a problem.
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To use
structuredCloneas part of the core, we would have to rewritenotify, which would add about 20 bytes to theatom, just to supportdeepMapmutability.I think until we make
notifya public API, it's better to usestructuredCloneonly insidedeepMap.