TypeScript错误无法读取未定义的属性“ REPOSITORY”

Question

New to TypeScript (but not to OO Design) I don't understand what happens

file application.ts

class
    APPLICATION{

        constructor(){
            console.log("constructor APPLICATION")
            this.database = new REPOSITORY
        }

        database: REPOSITORY
}

new APPLICATION

import { REPOSITORY } from "./repository"

file repository.ts

export

class
    REPOSITORY {

        constructor() {
            console.log("constructor de REPOSITORY")
        }

}

ANd I get the error

    this.database = new repository_1.REPOSITORY;
                                    ^

TypeError: Cannot read property 'REPOSITORY' of undefined at new APPLICATION (Z:\\Documents\\Phi\\Developpement\\TypeScript\\test\\application.js:6:41)

Any Idea ?

Answer 1

You are perfectly right ! I thought that the compiler was in two-passes and that the order of these statements were not imposed. As I think that this import/export mecanism should be automatic, I would prefer to hide it at the end of the code ! Too bad !

Thank you

Answer 2

Your import statement for REPOSITORY occurs after REPOSITORY is used in the constructor for APPLICATION , which means that it is not yet defined in the constructor (the variable assignment resulting from the import statement is not hoisted). You will need to import prior to use:

import { REPOSITORY } from "./repository"

class APPLICATION {
    constructor(){
        console.log("constructor APPLICATION")
        this.database = new REPOSITORY();
    }
    database: REPOSITORY
}

Answer 3

I don't believe imports are hoisted. Try moving import { REPOSITORY } from "./repository" up in your code.