Why Do Namespaces Behave Unexpectedly in TypeScript External Modules?

External Modules and Namespaces

Contrary to intuition, namespaces in TypeScript external modules, as demonstrated by the code snippet, yield unexpected behavior. This is a misconception rooted in the misguided use of namespaces for module organization and name collision prevention.

To understand why, consider the following candy analogy:

Candy Cup Analogy: Misconceptions

• Version 1: Individual Cups for Each Candy: Each module has its own namespace, effectively isolating them with no meaningful organization.
• Version 2: One Shared Cup for All Candies: This scenario simulates a global namespace that merges all types, which is not applicable to modules that operate in separate scopes.

Rejection of Namespaces for Modules

• Organization: Modules inherently provide file system-based organization, making namespaces redundant.
• Name Collisions: Modules eliminate this concern since they prevent type name collisions within their scope.

Alternative Module Organization Guidelines

• Export Close to Top-Level: Use export default for single exports and place multiple exports at the top level.
• Use Namespace Modules Only for Large Export Sets: Consider using namespace modules only when exporting a large number of entities.

Red Flags for Inappropriate Module Structure

• Export modules that define nothing but another module declaration (move exports to top level).
• Use export class or export function without export default for single exports.
• Multiple files with identical export module declarations (they do not merge).

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