Document break, @label and continue more thoroughly#60818
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jakobnissen wants to merge 6 commits intoJuliaLang:masterfrom
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Document break, @label and continue more thoroughly#60818jakobnissen wants to merge 6 commits intoJuliaLang:masterfrom
break, @label and continue more thoroughly#60818jakobnissen wants to merge 6 commits intoJuliaLang:masterfrom
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nsajko
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Jan 25, 2026
| Because structured control flow is easier to reason about than goto statements, | ||
| goto statements should generally be avoided, and only reached for in the rare cases | ||
| where the ordinary control flow mechanisms will not suffice. | ||
| One such example is optimized state machines. |
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This suggestion is perhaps excessively wordy, use what you like from it:
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| One such example is optimized state machines. | |
| An example application where it is cleanest to reach for `@goto` is translating an arbitrary finite state machine (FSM) into Julia code. Even so, some classes of FSM have a natural representation in structured control-flow, see the following paper for an example: [^codeFSM]. | |
| [^codeFSM]: | |
| Jones, D.W., 1988. How (not) to code a finite state machine. ACM SIGPlan Notices, 23(8), pp.19-22. |
NB: IMO it is not appropriate to use "optimized" here, so this suggestion removes the word. It is natural to reach for @goto when implementing a state machine, however this has less to do with performance, rather it leads to cleaner code.
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I disagree - the easiest way to write a FSM is to use an integer as state, and then have a main loop with a big if/ifelse/else chain matching the integer. In my opinion, this is less verbose and easier to follow than a goto-based state machine, but is less efficient.
nsajko
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Jan 25, 2026
Keno
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Jan 26, 2026
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Test failures seem unrelated |
* Rephrase `break` docstring to mention named break breaks from a named block in general, and not a loop. * Add a compat note to both `break` and `continue` docstrings * In break docstring, also include simple non-labeled usage example * In break docstring, also include non-loop code block break * In break docstring, highlight the returned value of `break name value` * Minor rephrasing of the newly added Manual section
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Documentation was largely missing from #60481.
Also document
@goto, which was not in the manual.