Forbid readContext() during render-phase class setState() reducer form #14670
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gaearon
commented
Jan 23, 2019
| expect(ReactNoop.flush).toThrow( | ||
| 'Context can only be read while React is rendering', | ||
| ), | ||
| ).toWarnDev('Cannot update during an existing state transition', { |
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We warn anyway so maybe it isn't worth it?
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The reason to do this is because the semantics are currently undefined — what happens when context changes? Re-rendering will have no effect because the update already happened — and we want to preserve option value to possibly support it properly in the future. Like for code splitting reducers. Same reason we warn about reading context inside Hook reducer.
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Generated by 🚫 dangerJS |
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That's true but we already unconditionally warn for render phase I guess we probably mute that warning at FB though? |
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Added a comment that I don’t think we should do this in prod. |
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Yeah warning is sufficient |
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Do we need an extra warning for this specifically? This test already warns with "Cannot update during an existing state transition". |
gaearon
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I made this depend on #14672 and added a similar DEV-only warning on top. |
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It's annoying to have so many small ones. I'll send a combined one. |
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Superseded by #14677 |
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Depends on #14672
Addresses #14653 (comment) (I think?)
Not sure we want to actually do it but figured I'd send a PR.