33 lines
1.8 KiB
Markdown
33 lines
1.8 KiB
Markdown
# Static anonymous functions
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## Summary
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Allow a 'static' modifier on lambdas and anonymous methods, which disallows capture of locals or instance state from containing scopes.
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## Motivation
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Avoid unintentionally capturing state from the enclosing context, which can result in unexpected retention of captured objects or unexpected additional allocations.
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## Detailed design
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A lambda or anonymous method may have a `static` modifier. The `static` modifier indicates that the lambda or anonymous method is a *static anonymous function*.
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A *static anonymous function* cannot capture state from the enclosing scope.
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As a result, locals, parameters, and `this` from the enclosing scope are not available within a *static anonymous function*.
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A *static anonymous function* cannot reference instance members from an implicit or explicit `this` or `base` reference.
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A *static anonymous function* may reference `static` members from the enclosing scope.
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A *static anonymous function* may reference `constant` definitions from the enclosing scope.
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`nameof()` in a *static anonymous function* may reference locals, parameters, or `this` or `base` from the enclosing scope.
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Accessibility rules for `private` members in the enclosing scope are the same for `static` and non-`static` anonymous functions.
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No guarantee is made as to whether a *static anonymous function* definition is emitted as a `static` method in metadata. This is left up to the compiler implementation to optimize.
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A non-`static` local function or anonymous function can capture state from an enclosing *static anonymous function* but cannot capture state outside the enclosing *static anonymous function*.
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Removing the `static` modifier from an anonymous function in a valid program does not change the meaning of the program.
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