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https://github.com/vercel-labs/scriptc.git
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Chris Tate
858328703b
The first Object.freeze, Object.seal or Object.preventExtensions of a typed function creates its property table from the function's dynamic box. The box had no name, so later `f.name` reads answered "". The box now carries the function's JS name, as a closure flowing into any checked-dynamic slot does. The runtime's own callers (published values, os and node constants, the private-range block list, Wasm exports) freeze data they built, and now call scr_dyn_freeze_data, the freeze for values that are not functions. Object.isFrozen, Object.isSealed and Object.isExtensible read a function's existing table and answer false, false and true when it has none. Fully typed programs therefore link no dynamic-tier object code for these calls again.
22 lines
1.0 KiB
TypeScript
22 lines
1.0 KiB
TypeScript
// Integrity operations on typed functions keep their names: the first one
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// creates the function's property table, whose `name` must be the
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// function's own. Queries on functions no operation has touched answer
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// without creating a table.
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function hashC(x: number): number {
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return x + 1;
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}
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const arrow = (s: string): string => s + "!";
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const untouched = (a: number, b: number): number => a * b;
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console.log(Object.isFrozen(untouched), Object.isSealed(untouched), Object.isExtensible(untouched));
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Object.freeze(hashC);
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Object.seal(arrow);
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console.log(Object.isFrozen(hashC), Object.isSealed(hashC), Object.isExtensible(hashC), hashC(1));
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console.log(Object.isFrozen(arrow), Object.isSealed(arrow), Object.isExtensible(arrow), arrow("a"));
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function later(): number {
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return 7;
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}
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Object.preventExtensions(later);
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console.log(Object.isFrozen(later), Object.isSealed(later), Object.isExtensible(later), later());
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const functions: any[] = [hashC, arrow, untouched, later];
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console.log(functions.map((f) => `${f.name}/${f.length}`).join(" "));
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