24 lines
1.1 KiB
Markdown
24 lines
1.1 KiB
Markdown
Side-Effect Considerations for Full Optimization Level
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======================================================
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{{#include ../../links.md}}
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All of Rhai's built-in functions (and operators which are implemented as functions) are _pure_
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(i.e. they do not mutate state nor cause any side-effects, with the exception of `print` and `debug`
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which are handled specially) so using [`OptimizationLevel::Full`] is usually quite safe _unless_
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custom types and functions are registered.
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If custom functions are registered, they _may_ be called (or maybe not, if the calls happen to lie
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within a pruned code block).
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If custom functions are registered to overload [built-in operators], they will also be called when
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the operators are used (in an [`if`] statement, for example), potentially causing side-effects.
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```admonish tip.small "Rule of thumb"
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* _Always_ register custom types and functions _after_ compiling scripts if [`OptimizationLevel::Full`] is used.
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* _DO NOT_ depend on knowledge that the functions have no side-effects, because those functions can change later on and,
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when that happens, existing scripts may break in subtle ways.
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```
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