I'm currently working on creating TypeScript type definitions for the StarUML tool. While I've been successful in defining most of the API, I've hit a roadblock when it comes to linking a JavaScript global variable ("type" in this case) with a TypeScript namespace that contains classes.
(A) The Issue at Hand
Within StarUML, there exists a global variable called type which registers numerous classes from unknown sources. For example, both type.Element and type.Model are classes (not elements). These two types are commonly used in JavaScript statements like if (x instanceof type.Element).
- In JavaScript, these classes are typically utilized in statements like
if (x instanceof type.Element). - In TypeScript, my goal is to define signatures such as
f(e : type.Element)and enable intelli-sense features for expressions likemyElement._id(where_idis an attribute of the classElement).
(B) Initial Attempt: Treating "type" as a Variable
Initially, I attempted to treat the type as a variable:
// type.d.ts
declare class Element {
_id: string
// ...
}
declare class Model extends Element {
name: string
// ...
}
declare const type = {
"Element" = Element,
"Model" = Model
// ...
}
However, this approach led to the following error:
S1254: A 'const' initializer in an ambient context must be a string or numeric literal or literal enum reference
Despite its limitations, this solution highlighted the essence of type: a registry linking class names to their respective classes.
(C) Revised Approach: Defining "type" as a Namespace
After poring over the TypeScript documentation and multiple attempts, I formulated a TypeScript file named types.d.ts, where I structured the code as follows:
// types.ts
export namespace type {
class Element {
_id: string
// ...
}
class Model extends Element {
name: string
}
// ...
}
(D) Usage in Client Code
Below is an illustrative code snippet (main.ts) employing this API definition. Both type.d.ts and main.ts reside at the top level for simplicity.
// (1) /// <reference path="./types.d.ts" />
// (2) import {type} from "./types"
// (3) declare var type
function hello(m: type.Element): void {
console.log(" hello: (" + e._id + ')')
}
console.log(type)
console.log(type.Element)
Despite several permutations of uncommenting lines, I'm yet to achieve all desired functionalities simultaneously.
(D.2) Expected vs. Actual Results
- (a) Properly defined types within the
function helloshould exhibit proper TypeScript behavior. - (b) Intelli-sense capabilities should function seamlessly for expressions like
e._id. - (c) The last line ought to accurately display the
type.Elementclass.
Frustratingly, achieving these goals concurrently has proven elusive, despite various importing strategies.
(D.3) Current Challenges
(1) Implementing line (1)
/// <reference ...has proved particularly challenging, even after exploring solutions like leveragingtsconfigsettings.(2) Although
import {type} ...appears promising for namespaces,console.log(type.element)returns undefined at runtime.(3) Declaring
var typeleads to functional JavaScript code but complicates matters further due to conflicts.
Simultaneous presence of (2) and (3) triggers TypeScript errors owing to conflicts arising from the dual nature of type as both a namespace and a variable.
(D.4) Seeking Resolutions
Despite extensive research into TypeScript resources and related blogs, clarity eludes me. Uncertainty looms over whether the issue lies in my implementation approach (as in section C) by treating the variable type as a namespace, or if challenges arise during compilation/runtime while invoking this namespace/variable.