Module Exports Patterns

🚨 CRITICAL RULES

1. Factory Function is Primary Export

Every module's src/index.ts MUST export a factory function:

typescript

export function newServiceName(): ServiceImpl {
  return new ServiceImpl();
}

Rules:

•✅ Named export (NOT default export)
•✅ Function name starts with new
•✅ Returns Impl instance (which implements Connector)
•✅ No parameters
•❌ NEVER use default export

2. Re-export Generated Types

MUST re-export all generated types:

typescript

// Re-export all generated API interfaces and wrappers
export * from '../generated/api';

// Re-export all generated models
export * from '../generated/model';

Why:

•Consumers need access to types
•ConnectionProfile, ConnectionState, etc.
•Resource models (User, Group, etc.)
•Don't pick specific types - export all

3. Minimal Public API

ONLY export what consumers actually need:

Export:

•✅ Factory function
•✅ Generated types (api.ts, model.ts)
•✅ Custom profile types (if any)
•✅ Custom error types (if any)

DO NOT export:

•❌ Client class (internal implementation)
•❌ Producer implementation classes (internal)
•❌ Mapper functions (internal)
•❌ Helper/utility functions (internal)
•❌ HTTP interceptors (internal)

🟡 STANDARD RULES

Standard index.ts Template

Basic pattern:

typescript

// src/index.ts

// Import Impl class
import { ServiceImpl } from './ServiceImpl';

// ========================================
// Factory Function (Primary Export)
// ========================================

/**
 * Creates a new Service connector instance
 * @returns ServiceImpl instance that implements ServiceConnector
 */
export function newServiceName(): ServiceImpl {
  return new ServiceImpl();
}

// ========================================
// Generated Exports
// ========================================

// Re-export all generated API interfaces and wrappers
export * from '../generated/api';

// Re-export all generated models
export * from '../generated/model';

// ========================================
// Custom Type Exports (if needed)
// ========================================

// Export custom profile types if you have them
// export type { CustomProfile } from './ServiceClient';

// Export custom error types if you have them
// export type { CustomError } from './errors';

Factory Function Naming

Pattern: new + PascalCase service name

Examples:

typescript

// GitHub module
export function newGitHub(): GitHubImpl

// Avigilon Alta Access module
export function newAvigilonAltaAccess(): AccessImpl

// Slack module
export function newSlack(): SlackImpl

// Azure Active Directory module
export function newAzureActiveDirectory(): AzureActiveDirectoryImpl

Rules:

•✅ Always starts with new
•✅ Service name in PascalCase
•✅ Full service name (not abbreviated)
•✅ Returns Impl class
•❌ No abbreviations (newAAD ❌, newAzureActiveDirectory ✅)

What Gets Re-exported from generated/

From ../generated/api.ts:

typescript

export * from '../generated/api';

This exports:

•ServiceConnector interface
•<Resource>Api interfaces (UserApi, GroupApi, etc.)
•wrap<Resource>Producer functions
•Type definitions for all operations

From ../generated/model.ts:

typescript

export * from '../generated/model';

This exports:

•ConnectionProfile type
•ConnectionState type
•Resource types (User, Group, Acu, etc.)
•Request/Response types
•Enum types

Optional Exports

Export Impl class (optional):

typescript

// Export implementation class for advanced usage
export { ServiceImpl } from './ServiceImpl';

When to export:

•✅ If consumers might need to extend it
•✅ If consumers need type for instance checks
•⚠️ Usually not necessary - factory function is enough

Export Client class (rarely):

typescript

// Export client for advanced/testing usage
export { ServiceClient } from './ServiceClient';

When to export:

•⚠️ Rarely needed
•⚠️ Only if consumers need direct access for testing
•⚠️ Generally keep Client internal

Export mappers (for testing):

typescript

// Export mappers for testing/debugging
export * from './Mappers';

When to export:

•✅ If consumers might need to test mappings
•✅ If mappers are useful utilities
•⚠️ Consider if mappers should be internal

Custom Type Exports

If you have custom ConnectionProfile extensions:

typescript

// ServiceClient.ts
export interface ServiceProfile extends ConnectionProfile {
  region?: string;
  customSetting?: boolean;
}

// index.ts
export type { ServiceProfile } from './ServiceClient';

If you have custom error types:

typescript

// errors.ts
export class ServiceSpecificError extends Error {
  constructor(message: string) {
    super(message);
    this.name = 'ServiceSpecificError';
  }
}

// index.ts
export { ServiceSpecificError } from './errors';

Export Organization

Group exports by purpose with comments:

typescript

// src/index.ts

import { ServiceImpl } from './ServiceImpl';

// ========================================
// Factory Function
// ========================================

export function newServiceName(): ServiceImpl {
  return new ServiceImpl();
}

// ========================================
// Implementation Classes (for advanced usage)
// ========================================

export { ServiceImpl } from './ServiceImpl';
// export { ServiceClient } from './ServiceClient';  // Uncomment if needed

// ========================================
// Generated Types
// ========================================

export * from '../generated/api';
export * from '../generated/model';

// ========================================
// Mappers (for testing)
// ========================================

export * from './Mappers';

// ========================================
// Custom Types
// ========================================

// export type { ServiceProfile } from './ServiceClient';
// export { ServiceSpecificError } from './errors';

🟢 GUIDELINES

Type Safety in Exports

Factory function should have return type:

typescript

// ✅ GOOD: Explicit return type
export function newServiceName(): ServiceImpl {
  return new ServiceImpl();
}

// ⚠️ OK but less clear
export function newServiceName() {
  return new ServiceImpl();
}

Why:

•Explicit type helps consumers
•IDE autocomplete works better
•Catches return type errors

Default Exports (Don't Use)

❌ WRONG: Default export

typescript

export default function newServiceName() {
  return new ServiceImpl();
}

✅ CORRECT: Named export

typescript

export function newServiceName(): ServiceImpl {
  return new ServiceImpl();
}

Why:

•Named exports are more explicit
•Better for tree-shaking
•Easier to find usages
•Consistent with TypeScript best practices

Consumer Usage Pattern

How consumers use your module:

typescript

// Consumer code
import {
  newServiceName,
  ConnectionProfile,
  UserApi,
  User
} from '@auditmation/connector-vendor-service';

// Create connector using factory
const connector = newServiceName();

// Use ConnectionProfile type
const profile: ConnectionProfile = {
  apiKey: process.env.API_KEY!
};

// Connect
await connector.connect(profile);

// Get typed API
const userApi: UserApi = connector.getUserApi();

// Get typed resources
const users: User[] = await userApi.listUsers();

What they need:

•Factory function - newServiceName()
•Profile type - ConnectionProfile
•API interfaces - UserApi
•Resource types - User

All of these come from your exports!

Documentation Comments

Add JSDoc to factory function:

typescript

/**
 * Creates a new Service connector instance.
 *
 * @returns A new connector instance that implements ServiceConnector
 *
 * @example
 * ```typescript
 * import { newServiceName } from '@auditmation/connector-vendor-service';
 *
 * const connector = newServiceName();
 * await connector.connect({ apiKey: 'your-key' });
 * ```
 */
export function newServiceName(): ServiceImpl {
  return new ServiceImpl();
}

Benefits:

•Shows up in IDE tooltips
•Documents usage
•Provides example

Impl Class Export Pattern

If exporting Impl, also export it directly:

typescript

// Option 1: Export from source
export { ServiceImpl } from './ServiceImpl';

// Option 2: Re-export from factory
import { ServiceImpl } from './ServiceImpl';

export function newServiceName(): ServiceImpl {
  return new ServiceImpl();
}

export { ServiceImpl };  // Also export class

Enables type checking:

typescript

// Consumer code
import { newServiceName, ServiceImpl } from '@auditmation/connector';

const connector = newServiceName();

if (connector instanceof ServiceImpl) {
  // TypeScript knows the type
}

Validation

Check Factory Function Exists

bash

# Check factory function exists
if [ -f src/index.ts ]; then
  if grep -q "export function new" src/index.ts; then
    echo "✅ PASS: Factory function exists"
  else
    echo "❌ FAIL: No factory function found"
    exit 1
  fi
else
  echo "❌ FAIL: src/index.ts not found"
  exit 1
fi

Check Factory Function Naming

bash

# Check factory function follows naming convention
FACTORY_NAME=$(grep "export function new" src/index.ts | sed -E 's/.*function (new[A-Za-z]+).*/\1/')

if [[ "$FACTORY_NAME" =~ ^new[A-Z] ]]; then
  echo "✅ PASS: Factory function named: $FACTORY_NAME"
else
  echo "❌ FAIL: Factory function must start with 'new' + PascalCase"
  exit 1
fi

Check Generated Exports

bash

# Check re-exports from generated/
if grep -q "export \* from.*generated" src/index.ts; then
  echo "✅ PASS: Re-exports generated types"
else
  echo "❌ FAIL: Must re-export from ../generated/"
  exit 1
fi

# Check both api and model exports
if grep -q "export \* from.*generated/api" src/index.ts; then
  echo "✅ PASS: Exports generated/api"
else
  echo "⚠️ WARN: Should export from ../generated/api"
fi

if grep -q "export \* from.*generated/model" src/index.ts; then
  echo "✅ PASS: Exports generated/model"
else
  echo "⚠️ WARN: Should export from ../generated/model"
fi

Check No Internal Exports

bash

# Check NOT exporting Client class (usually internal)
if grep -q "export.*Client.*from.*Client" src/index.ts | grep -v "//"; then
  echo "⚠️ WARN: Exporting Client class (usually should be internal)"
else
  echo "✅ PASS: Client class not exported (good - keep internal)"
fi

# Check for default exports (should not use)
if grep -q "export default" src/index.ts; then
  echo "❌ FAIL: Using default export (use named exports)"
  exit 1
else
  echo "✅ PASS: No default exports (good)"
fi

Check Return Type

bash

# Check factory function has return type
if grep -q "export function new.*().*:" src/index.ts; then
  echo "✅ PASS: Factory function has return type"
else
  echo "⚠️ WARN: Factory function should have explicit return type"
fi

Complete Validation Script

bash

#!/bin/bash
# validate-exports.sh - Validate index.ts exports

echo "=== Module Exports Validation ==="
echo ""

if [ ! -f src/index.ts ]; then
  echo "❌ FAIL: src/index.ts not found"
  exit 1
fi

echo "Checking: src/index.ts"
echo ""

ERRORS=0

# 1. Factory function
echo "1. Factory Function:"
if grep -q "export function new" src/index.ts; then
  FACTORY=$(grep "export function new" src/index.ts | head -1)
  echo "  ✅ Found: $FACTORY"

  # Check naming
  if echo "$FACTORY" | grep -q "export function new[A-Z]"; then
    echo "  ✅ Correct naming (new + PascalCase)"
  else
    echo "  ❌ Wrong naming (must be new + PascalCase)"
    ERRORS=$((ERRORS + 1))
  fi

  # Check return type
  if echo "$FACTORY" | grep -q "):"; then
    echo "  ✅ Has return type"
  else
    echo "  ⚠️  Should have explicit return type"
  fi
else
  echo "  ❌ Factory function missing"
  ERRORS=$((ERRORS + 1))
fi
echo ""

# 2. Generated exports
echo "2. Generated Exports:"
if grep -q "export \* from.*generated" src/index.ts; then
  echo "  ✅ Re-exports from generated/"

  if grep -q "export \* from.*generated/api" src/index.ts; then
    echo "  ✅ Exports ../generated/api"
  else
    echo "  ⚠️  Should export ../generated/api"
  fi

  if grep -q "export \* from.*generated/model" src/index.ts; then
    echo "  ✅ Exports ../generated/model"
  else
    echo "  ⚠️  Should export ../generated/model"
  fi
else
  echo "  ❌ Must re-export from generated/"
  ERRORS=$((ERRORS + 1))
fi
echo ""

# 3. Export style
echo "3. Export Style:"
if grep -q "export default" src/index.ts; then
  echo "  ❌ Uses default export (should use named exports)"
  ERRORS=$((ERRORS + 1))
else
  echo "  ✅ No default exports (good)"
fi

# Count named exports
EXPORT_COUNT=$(grep -c "^export" src/index.ts)
echo "  ✅ $EXPORT_COUNT export statements"
echo ""

# 4. Internal exports check
echo "4. Internal Exports (warnings):"
if grep -q "export.*Client" src/index.ts | grep -v "^//"; then
  echo "  ⚠️  Exporting Client (usually internal)"
else
  echo "  ✅ Client not exported"
fi

if grep -q "export.*Mapper" src/index.ts | grep -v "^//"; then
  echo "  ⚠️  Exporting Mappers (check if needed)"
else
  echo "  ✅ Mappers not exported"
fi
echo ""

# 5. File size check (should be small)
LINE_COUNT=$(wc -l < src/index.ts)
if [ "$LINE_COUNT" -lt 50 ]; then
  echo "5. File Size: ✅ $LINE_COUNT lines (good - index.ts should be small)"
else
  echo "5. File Size: ⚠️ $LINE_COUNT lines (large - consider if all exports are needed)"
fi
echo ""

# Summary
if [ $ERRORS -eq 0 ]; then
  echo "=== ✅ VALIDATION PASSED ==="
  exit 0
else
  echo "=== ❌ VALIDATION FAILED ($ERRORS errors) ==="
  exit 1
fi

Common Issues

Issue: No factory function

Problem:

typescript

// index.ts
export { ServiceImpl } from './ServiceImpl';

Solution:

typescript

import { ServiceImpl } from './ServiceImpl';

export function newServiceName(): ServiceImpl {
  return new ServiceImpl();
}

export * from '../generated/api';
export * from '../generated/model';

Issue: Using default export

Problem:

typescript

export default function newServiceName() {
  return new ServiceImpl();
}

Solution:

typescript

export function newServiceName(): ServiceImpl {
  return new ServiceImpl();
}

Issue: Not re-exporting generated types

Problem:

typescript

// Only exports factory
export function newServiceName(): ServiceImpl {
  return new ServiceImpl();
}

Solution:

typescript

export function newServiceName(): ServiceImpl {
  return new ServiceImpl();
}

// Add these
export * from '../generated/api';
export * from '../generated/model';

Issue: Exporting too much

Problem:

typescript

// Exporting everything
export * from './ServiceImpl';
export * from './ServiceClient';
export * from './helpers';
export * from './utils';
export * from './mappers';
export * from './errors';

Solution:

typescript

// Minimal public API
export function newServiceName(): ServiceImpl {
  return new ServiceImpl();
}

export * from '../generated/api';
export * from '../generated/model';

// Only export what consumers truly need

Anti-Patterns

❌ BAD: Complex factory with parameters

typescript

export function newServiceName(config: ServiceConfig): ServiceImpl {
  return new ServiceImpl(config);
}

✅ GOOD: Simple factory, no parameters

typescript

export function newServiceName(): ServiceImpl {
  return new ServiceImpl();
}

❌ BAD: Multiple factory functions

typescript

export function newServiceName(): ServiceImpl { ... }
export function createServiceName(): ServiceImpl { ... }
export function makeServiceName(): ServiceImpl { ... }

✅ GOOD: Single factory function

typescript

export function newServiceName(): ServiceImpl {
  return new ServiceImpl();
}

❌ BAD: Selective type exports

typescript

// Don't cherry-pick types
export { ConnectionProfile, UserApi } from '../generated/api';
export { User, Group } from '../generated/model';

✅ GOOD: Export all generated types

typescript

// Export everything
export * from '../generated/api';
export * from '../generated/model';

❌ BAD: Exporting implementation details

typescript

export { ServiceClient } from './ServiceClient';
export { httpInterceptor } from './interceptors';
export { mapUser, mapGroup } from './mappers';
export { validateProfile } from './validators';

✅ GOOD: Minimal public API

typescript

export function newServiceName(): ServiceImpl {
  return new ServiceImpl();
}

export * from '../generated/api';
export * from '../generated/model';

// Keep internals private