357bd87612
If each type in U has a property P, U has a property P of a union type of the types of P from each type in U.
80 lines
3.2 KiB
TypeScript
80 lines
3.2 KiB
TypeScript
//// [unionTypeMembers.ts]
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interface I1<T> {
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commonMethodType(a: string): string;
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commonPropertyType: string;
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commonMethodDifferentParameterType(a: string): string;
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commonMethodDifferentReturnType(a: string): string;
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commonPropertyDifferenType: string;
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commonMethodWithTypeParameter(a: T): T;
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commonMethodWithOwnTypeParameter<U>(a: U): U;
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methodOnlyInI1(a: string): string;
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propertyOnlyInI1: string;
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}
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interface I2<T> {
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commonMethodType(a: string): string;
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commonPropertyType: string;
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commonMethodDifferentParameterType(a: number): number;
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commonMethodDifferentReturnType(a: string): number;
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commonPropertyDifferenType: number;
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commonMethodWithTypeParameter(a: T): T;
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commonMethodWithOwnTypeParameter<U>(a: U): U;
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methodOnlyInI2(a: string): string;
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propertyOnlyInI2: string;
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}
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// a union type U has those members that are present in every one of its constituent types,
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// with types that are unions of the respective members in the constituent types
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var x : I1<number> | I2<number>;
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var str: string;
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var num: number;
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var strOrNum: string | number;
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// If each type in U has a property P, U has a property P of a union type of the types of P from each type in U.
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str = x.commonPropertyType; // string
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str = x.commonMethodType(str); // (a: string) => string so result should be string
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strOrNum = x.commonPropertyDifferenType;
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strOrNum = x.commonMethodDifferentReturnType(str); // string | union
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x.commonMethodDifferentParameterType; // No error - property exists
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x.commonMethodDifferentParameterType(strOrNum); // error - no call signatures because the type of this property is ((a: string) => string) | (a: number) => number
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// and the call signatures arent identical
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num = x.commonMethodWithTypeParameter(num);
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num = x.commonMethodWithOwnTypeParameter(num);
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str = x.commonMethodWithOwnTypeParameter(str);
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strOrNum = x.commonMethodWithOwnTypeParameter(strOrNum);
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x.propertyOnlyInI1; // error
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x.propertyOnlyInI2; // error
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x.methodOnlyInI1("hello"); // error
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x.methodOnlyInI2(10); // error
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//// [unionTypeMembers.js]
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// a union type U has those members that are present in every one of its constituent types,
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// with types that are unions of the respective members in the constituent types
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var x;
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var str;
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var num;
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var strOrNum;
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// If each type in U has a property P, U has a property P of a union type of the types of P from each type in U.
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str = x.commonPropertyType; // string
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str = x.commonMethodType(str); // (a: string) => string so result should be string
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strOrNum = x.commonPropertyDifferenType;
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strOrNum = x.commonMethodDifferentReturnType(str); // string | union
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x.commonMethodDifferentParameterType; // No error - property exists
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x.commonMethodDifferentParameterType(strOrNum); // error - no call signatures because the type of this property is ((a: string) => string) | (a: number) => number
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// and the call signatures arent identical
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num = x.commonMethodWithTypeParameter(num);
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num = x.commonMethodWithOwnTypeParameter(num);
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str = x.commonMethodWithOwnTypeParameter(str);
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strOrNum = x.commonMethodWithOwnTypeParameter(strOrNum);
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x.propertyOnlyInI1; // error
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x.propertyOnlyInI2; // error
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x.methodOnlyInI1("hello"); // error
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x.methodOnlyInI2(10); // error
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