initial commit

inject.test.ts

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+import { assertEquals } from "https://deno.land/std@0.223.0/assert/mod.ts";
+import { inject } from "./inject.ts";
+
+function toInject(
+  p1: number,
+  p2: number,
+  p3: number,
+  p4: number,
+  p5: number,
+  p6: number,
+  p7: number,
+  p8: number,
+  p9: number,
+) {
+  return [
+    p1,
+    p2,
+    p3,
+    p4,
+    p5,
+    p6,
+    p7,
+    p8,
+    p9,
+  ];
+}
+
+const expectedResult = [
+  1,
+  2,
+  3,
+  4,
+  5,
+  6,
+  7,
+  8,
+  9,
+]
+
+Deno.test("inject with single parameter", () => {
+  const injected = inject(toInject, 1);
+  const result = injected(2, 3, 4, 5, 6, 7, 8, 9);
+  assertEquals(result, expectedResult);
+});
+
+Deno.test("inject with two parameters", () => {
+  const injected = inject(toInject, 1, 2);
+  const result = injected(3, 4, 5, 6, 7, 8, 9);
+  assertEquals(result, expectedResult);
+});
+
+Deno.test("inject with three parameters", () => {
+  const injected = inject(toInject, 1, 2, 3);
+  const result = injected(4, 5, 6, 7, 8, 9);
+  assertEquals(result, expectedResult);
+});
+
+Deno.test("inject with four parameters", () => {
+  const injected = inject(toInject, 1, 2, 3, 4);
+  const result = injected(5, 6, 7, 8, 9);
+  assertEquals(result, expectedResult);
+});
+
+Deno.test("inject with five parameters", () => {
+  const injected = inject(toInject, 1, 2, 3, 4, 5);
+  const result = injected(6, 7, 8, 9);
+  assertEquals(result, expectedResult);
+});
+
+Deno.test("inject with six parameters", () => {
+  const injected = inject(toInject, 1, 2, 3, 4, 5, 6);
+  const result = injected(7, 8, 9);
+  assertEquals(result, expectedResult);
+});
+
+Deno.test("inject with seven parameters", () => {
+  const injected = inject(toInject, 1, 2, 3, 4, 5, 6, 7);
+  const result = injected(8, 9);
+  assertEquals(result, expectedResult);
+});
+
+Deno.test("inject with eight parameters", () => {
+  const injected = inject(toInject, 1, 2, 3, 4, 5, 6, 7, 8);
+  const result = injected(9);
+  assertEquals(result, expectedResult);
+});
+
+Deno.test("inject with nine parameters", () => {
+  const injected = inject(toInject, 1, 2, 3, 4, 5, 6, 7, 8, 9);
+  const result = injected();
+  assertEquals(result, expectedResult);
+});

inject.ts

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+/**
+ * Take a function and the first(s) parameter(s) to inject.
+ * Return a function that don't need those parameters.
+ *
+ * Example:
+ * ```
+ * function myFunc(a, b, c) {
+ *   // ...
+ * }
+ *
+ * const injected = inject(myFunc, "A", "B");
+ * injected("C"); // same result as myFunc("A", "B", "C")
+ * ```
+ */
+export function inject<P1, OtherParams extends any[], Result>(
+  subject: (p1: P1, ...params: OtherParams) => Result,
+  p1: P1,
+): (...params: OtherParams) => Result;
+export function inject<P1, P2, OtherParams extends any[], Result>(
+  subject: (p1: P1, p2: P2, ...params: OtherParams) => Result,
+  p1: P1,
+  p2: P2,
+): (...params: OtherParams) => Result;
+export function inject<P1, P2, P3, OtherParams extends any[], Result>(
+  subject: (p1: P1, p2: P2, p3: P3, ...params: OtherParams) => Result,
+  p1: P1,
+  p2: P2,
+  p3: P3,
+): (...params: OtherParams) => Result;
+export function inject<P1, P2, P3, P4, OtherParams extends any[], Result>(
+  subject: (p1: P1, p2: P2, p3: P3, p4: P4, ...params: OtherParams) => Result,
+  p1: P1,
+  p2: P2,
+  p3: P3,
+  p4: P4,
+): (...params: OtherParams) => Result;
+export function inject<P1, P2, P3, P4, P5, OtherParams extends any[], Result>(
+  subject: (p1: P1, p2: P2, p3: P3, p4: P4, p5: P5, ...params: OtherParams) => Result,
+  p1: P1,
+  p2: P2,
+  p3: P3,
+  p4: P4,
+  p5: P5,
+): (...params: OtherParams) => Result;
+export function inject<P1, P2, P3, P4, P5, P6, OtherParams extends any[], Result>(
+  subject: (p1: P1, p2: P2, p3: P3, p4: P4, p5: P5, p6: P6, ...params: OtherParams) => Result,
+  p1: P1,
+  p2: P2,
+  p3: P3,
+  p4: P4,
+  p5: P5,
+  p6: P6,
+): (...params: OtherParams) => Result;
+export function inject<P1, P2, P3, P4, P5, P6, P7, OtherParams extends any[], Result>(
+  subject: (p1: P1, p2: P2, p3: P3, p4: P4, p5: P5, p6: P6, p7: P7, ...params: OtherParams) => Result,
+  p1: P1,
+  p2: P2,
+  p3: P3,
+  p4: P4,
+  p5: P5,
+  p6: P6,
+  p7: P7,
+): (...params: OtherParams) => Result;
+export function inject<P1, P2, P3, P4, P5, P6, P7, P8, OtherParams extends any[], Result>(
+  subject: (p1: P1, p2: P2, p3: P3, p4: P4, p5: P5, p6: P6, p7: P7, p8: P8, ...params: OtherParams) => Result,
+  p1: P1,
+  p2: P2,
+  p3: P3,
+  p4: P4,
+  p5: P5,
+  p6: P6,
+  p7: P7,
+  p8: P8,
+): (...params: OtherParams) => Result;
+export function inject<P1, P2, P3, P4, P5, P6, P7, P8, P9, OtherParams extends any[], Result>(
+  subject: (p1: P1, p2: P2, p3: P3, p4: P4, p5: P5, p6: P6, p7: P7, p8: P8, p9: P9, ...params: OtherParams) => Result,
+  p1: P1,
+  p2: P2,
+  p3: P3,
+  p4: P4,
+  p5: P5,
+  p6: P6,
+  p7: P7,
+  p8: P8,
+  p9: P9,
+): (...params: OtherParams) => Result;
+export function inject<FirstParam, OtherParams extends any[], Result>(
+  subject: (first: FirstParam, ...params: OtherParams) => Result,
+  ...paramsToInject: any[]
+) {
+  return paramsToInject.reduce((functionToInjext, paramToInject) => {
+    return (...params: OtherParams) =>
+      functionToInjext(paramToInject, ...params);
+  }, subject) as (...param: OtherParams) => Result;
+}

mod.ts

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+export * from './inject.ts'

readme.md

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+# Function injection
+
+Provide a way to inject the first(s: up to nine) arguments in a function.
+
+Example:
+```typescript
+function myFunc(p1: string, p2: string, p3: string) {
+  console.log(p1, p2, p3)
+}
+
+const injected = inject(myFunc, "A", "B"); //< `injected` is a function that only take one argument
+injected("C"); //< same result as calling `myFunc("A", "B", "C")
+```