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32 lines
1.8 KiB
Markdown
32 lines
1.8 KiB
Markdown
# Deprecate table.getn/foreach/foreachi
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## Summary
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Mark table.getn/foreach/foreachi as deprecated
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## Motivation
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`table.getn` was deprecated in Lua 5.1 that Luau is based on.
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`table.getn(x)` is equivalent to `rawlen(x)` when `x` is a table; when `x` is not a table, `table.getn` produces an error. It's difficult to imagine code where `table.getn(x)` is better than either `#x` (idiomatic) or `rawlen(x)` (fully compatible replacement). However, `table.getn` is slower and provides yet another way to perform an operation, leading new users of the language to use it unknowingly.
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`table.foreach` and `table.foreachi` were deprecated in Lua 5.2.
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`table.foreach` is equivalent to a `for .. pairs` loop; `table.foreachi` is equivalent to a `for .. ipairs` loop; both may also be replaced by generalized iteration. Both functions are significantly slower than equivalent `for` loop replacements, are more restrictive because the function can't yield, and result in new users (particularly coming from JS background) unknowingly using these thus producing non-idiomatic non-performant code.
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In both cases, the functions bring no value over other library or language alternatives, and thus just serve as a distraction.
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## Design
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We will mark all three functions as deprecated. The only consequence of this change is that the linter will start emitting warnings when they are used.
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Removing support for these functions doesn't provide any measurable value and as such is not planned in the foreseeable future because it may cause backwards compatibility issues.
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## Drawbacks
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None
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## Alternatives
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If we consider table.getn/etc as supported, we'd want to start optimizing their usage which gets particularly tricky with foreach and requires more compiler machinery than this is probably worth.
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