microsoft / microsoft/TypeScript
Infer Generics Types, from Record<string<...> Aggregation for return type constraints
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Descripción
If you can imagine capturing type information at the same time as runtime information, were the inferred types literals match that those of the runtime types, so that one can implicitly at the same time
capture the typescript types and runtime information for the shape of the typescript type, in one shot.
This I have been doing quite successfully, and is quite powerfully. I find myself using what I term type constraints, to capture information at runtime in specific categories, that typings constraints impose. Which allows me to do advance record mixing.
This allows one to impose constraints on free form runtime information, to ensure
runtime information is correctly categorized for typing system performance of mixing.
Example of return type constraints for categorization for mixing
interface IConstraints<Param1 extends 'Param1A' | 'Param1B',
Param2 extends 'Param2A' | 'Param2B',
Param3 extends 'Param3A' | 'Param3B'> = {
__Param1 : Param1
__Param2 : Param2
__Param3 : Param3
}
// Typically Record< IConstraints.. Is a recursive record capture pattern, with neasted records
class RecordMix<
Dim1 extends Record<string, IConstraints<'Param1A',any,any>>,
Dim2 extends Record<string, IConstraints<'Param1A',any,any>,
Dim3 extends Record<string, IConstraints<never, 'Param2B','Param3A'>
Dim4 extends Record<string, IConstraints<never,'Param2A','Param3B'>
{
// Use the constructor to capture the runtime sets of information.
}
Functionality as of current.
interface Builder<A extends string, B extends string>
{
__A : A,
__B : B
}
type AString = 'A' | 'E' | 'G';
type BString = 'B' | 'F' | 'H';
type RecordBuilder<A extends AString, B extends BString> = Record<string, Builder<A,B>>
const builderRecord = {
a : {} as any as Builder<'A','B'>,
e : {} as any as Builder<'E','F'>,
// g : {} as any as Builder<'G','F'>,
}
const builderRecordInvalid = {
a : {} as any as Builder<'A','B'>,
e : {} as any as Builder<'E','F'>,
g : {} as any as Builder<'G','F'>,
}
function Capture<A extends 'A' |'E', B extends BString, Rec extends RecordBuilder<A, B>>(record : Rec)
{
return {} as any as {Ra:A,Rb:B};
}
const result = {a:Capture(builderRecord)} //OK
const result = {a:Capture(builderRecordInvalid)} //Failed input type constraints not met
// Type
const result: {
a: {
Ra: "A" | "E";
Rb: BString;
};
}
Functionality Feature Request, using infer of aggregate
function Capture<A extends 'A' |'E', B extends BString, Rec extends RecordBuilder<infer A, infer B>>(record : Rec)
{
return {} as any as {Ra:A,Rb:B};
}
const result = {a:Capture(builderRecord)} //OK
const result = {a:Capture(builderRecordInvalid)} //Failed input type constraints not met
// Type Results
const result: {
a: {
Ra: "A" | "E";
Rb: "B" | "F";
};
}
Functionality Feature Request current mechanisms
type ExtractRecordComponent<Shape extends Record<string,any>, T extends Record<string, Shape>, Key extends string> = ({
[K in keyof T] : T[K][Key]
})[keyof T]
function Capture<A extends 'A' |'E', B extends BString, Rec extends RecordBuilder<A, B>>(record : Rec)
: {Ra:ExtractRecordComponent<Builder<any,any>,Rec,'__A'>, Rb:ExtractRecordComponent<Builder<any,any>,Rec,'__B'>}
{
return {} as any;
}
const result = {a:Capture(builderRecord)} //OK
const result = {a:Capture(builderRecordInvalid)} //Failed input type constraints not met
// Type Results
const result: {
a: {
Ra: "A" | "E";
Rb: "B" | "F";
};
}
Checklist
My suggestion meets these guidelines:
- This wouldn't be a breaking change in existing TypeScript/JavaScript code
- This wouldn't change the runtime behavior of existing JavaScript code
- This could be implemented without emitting different JS based on the types of the expressions
- This isn't a runtime feature (e.g. library functionality, non-ECMAScript syntax with JavaScript output, etc.)
- This feature would agree with the rest of TypeScript's Design Goals.
Guía de contribución
Primeros pasos
- Lee el issue completo y luego la guía de contribución del proyecto.
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- Haz un fork del repositorio y trabaja en una rama.
- Abre un pull request que haga referencia al número del issue.
Línea de trabajo
El issue no menciona archivos fuente, pruebas ni puntos de entrada. Empieza por reducir los ejemplos de RecordBuilder y Capture a un caso mínimo de inferencia y, después, compara el comportamiento solicitado de aggregate infer con la solución alternativa actual basada en ExtractRecordComponent; el trabajo estaría terminado cuando existan reglas de inferencia precisas y pruebas para las entradas aceptadas y rechazadas indicadas.
Escrito por el modelo de indexación a partir del texto del issue.
Evaluación
- Stack tecnológico
- typescript
- Área
- compilers
- Tipo de issue
- Nueva funcionalidad
- Dificultad
- 5/5
- Tiempo estimado
- Más de una semana
- Estado de actividad
- Estancado
- Claridad
- Necesita aclaración
- Aptitud para principiantes
- 20/100