Working with Modules

Barrel API Shape

A barrel module gathers selected exports into a small public surface.

barrel module A barrel file re-exports a curated set of names so callers do not depend on every internal file.

Barrel API Shape

admin
barrel_api.ts
Replay: real traced execution (multi-file project)
function normalizeName(name: string): string {
    return name.trim().toLowerCase();
}

function formatUser(name: string, admin: boolean): string {
    const role: string = admin ? "admin" : "reader";
    return `${normalizeName(name)}:${role}`;
}

export const publicApi = {
    formatUser,
};

const admin: boolean = false;
const line: string = publicApi.formatUser(" ADA ", admin);

console.log(line);

function normalizeName(name: string): string {
    return name.trim().toLowerCase();
}

function formatUser(name: string, admin: boolean): string {
    const role: string = admin ? "admin" : "reader";
    return `${normalizeName(name)}:${role}`;
}

export const publicApi = {
    formatUser,
};

const admin: boolean = true;
const line: string = publicApi.formatUser(" ADA ", admin);

console.log(line);

  1. publicApi ← [object Object], admin ← false

    7    return `${normalizeName(name)}:${role}`;8}910export const publicApi→ [object Object] = {11    formatUser,12};1314const admin→ false: boolean = false;  //@admin=true15const line: string = publicApi[object Object].formatUser(" ADA ", adminfalse);

  2. role ← reader

    2    return name.trim().toLowerCase();3}45function formatUser(name ADA : string, adminfalse: boolean): string {6    const role→ reader: string = adminfalse ? "admin" : "reader";7    return `${normalizeName(name ADA )}:${rolereader}`;8}

  3. function normalizeName(name: string): string

    1function normalizeName(name ADA : string): string {2    return name ADA .trim().toLowerCase();3}

  4. line ← ada:reader

    14const admin: boolean = false;  //@admin=true15const line→ ada:reader: string = publicApi[object Object].formatUser(" ADA ", adminfalse);1617console.log(lineada:reader);
    outputada:reader

  1. publicApi ← [object Object], admin ← true

    7    return `${normalizeName(name)}:${role}`;8}910export const publicApi→ [object Object] = {11    formatUser,12};1314const admin→ true: boolean = true;15const line: string = publicApi[object Object].formatUser(" ADA ", admintrue);

  2. role ← admin

    2    return name.trim().toLowerCase();3}45function formatUser(name ADA : string, admintrue: boolean): string {6    const role→ admin: string = admintrue ? "admin" : "reader";7    return `${normalizeName(name ADA )}:${roleadmin}`;8}

  3. function normalizeName(name: string): string

    1function normalizeName(name ADA : string): string {2    return name ADA .trim().toLowerCase();3}

  4. line ← ada:admin

    14const admin: boolean = true;15const line→ ada:admin: string = publicApi[object Object].formatUser(" ADA ", admintrue);1617console.log(lineada:admin);
    outputada:admin