CODEWITHSUNDEEP
javascripttypescript
Nicklas Pouey-Winger
Nicklas Pouey-Winger

Reputation: 3023

Unable to resolve signature of Typescript decorator when imported from another file

Given the following:

decorator.ts

export function logStuff(target: Object, key: string | symbol, descriptor: TypedPropertyDescriptor<any>) {
    return {
        value: function (...args: any[]) {
            args.push("Another argument pushed");
            descriptor.value.apply(target, args);
        }
    };
}

Shell.ts

// Removed other imports for brevity
import logStuff = require("utils/log-decorator");

class Shell extends AnotherClass {
    constructor() {
        super();
        this.fooMethod("arg1");
    }

    @logStuff
    private fooMethod(arg1: string, arg2?: string) {
        console.log(`Arguments from original function: ${JSON.stringify(arguments)}`);
    }
}

export = Shell;

I get this message (shortened the file path for brevity):

Unable to resolve signature of method decorator when called as an expression. Cannot invoke an expression whose type lacks a call signature. Type 'typeof "/utils/log-decorator"' has no compatible call signatures

However, if I move the function to the top of Shell.ts, it compiles without errors. Any suggestions on how to handle this?

Upvotes: 1

Views: 2178

Answers (1)

Saravana
Saravana

Reputation: 40554

Your logStuff is available as an exported member of the module. So you have to access it like:

import logStuffModule = require("utils/log-decorator");
//...
@logStuffModule.logStuff
private fooMethod(arg1: string, arg2?: string) { ... }

Or use ES6-style imports:

import { logStuff }  from "utils/log-decorator";

// ...
@logStuff
private fooMethod(arg1: string, arg2?: string) { ... }

Or you can modify your module by setting the export object as your function and use it like how you are using it now:

// decorator.ts
export = function logStuff() {}

// Shell.ts    
import logStuff = require("utils/log-decorator");

// ...
@logStuff
private fooMethod(arg1: string, arg2?: string) { ... }

Upvotes: 3

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