52 lines
1.7 KiB
JavaScript
52 lines
1.7 KiB
JavaScript
'use strict';
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const errorHierarchy = require ('./errorHierarchy.js')
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/* ------------------------------------------------------------------------ */
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function subclass (BaseClass, classes, namespace = {}) {
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for (const [className, subclasses] of Object.entries (classes)) {
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const Class = Object.assign (namespace, {
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/* By creating a named property, we trick compiler to assign our class constructor function a name.
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Otherwise, all our error constructors would be shown as [Function: Error] in the debugger! And
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the super-useful `e.constructor.name` magic wouldn't work — we then would have no chance to
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obtain a error type string from an error instance programmatically! */
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[className]: class extends BaseClass {
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constructor (message) {
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super (message)
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/* A workaround to make `instanceof` work on custom Error classes in transpiled ES5.
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See my blog post for the explanation of this hack:
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https://medium.com/@xpl/javascript-deriving-from-error-properly-8d2f8f315801 */
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this.constructor = Class
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this.__proto__ = Class.prototype
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this.name = className
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this.message = message
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}
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}
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})[className]
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subclass (Class, subclasses, namespace)
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}
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return namespace
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}
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/* ------------------------------------------------------------------------ */
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module.exports = subclass (
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// Root class
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Error,
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// Derived class hierarchy
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errorHierarchy
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)
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