Description

Brent Erickson (berickson1)

opened on Jan 10, 2018

Issue body actions

TypeScript Version: 2.7.0-dev.20180110

Code

export class Test {
    private _foo: string;
    constructor() {
        this._init();
    }

    private _init() {
        this._foo = 'test';
    }
}

https://github.com/berickson1/Playground/blob/master/strictPropertyInitError.ts

Expected behavior:
Code compiles with strict flags on

Actual behavior:
strictPropertyInitError.ts(4,13): error TS2564: Property '_foo' has no initializer and is not definitely assigned in the constructor.

Activity

1. Ryan Cavanaugh (RyanCavanaugh)

   added

   Design LimitationConstraints of the existing architecture prevent this from being fixedConstraints of the existing architecture prevent this from being fixed

   on Jan 10, 2018
2. mhegazy commented on Jan 10, 2018

   

   Mohamed Hegazy (mhegazy)

   on Jan 10, 2018

   Contributor

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   The compiler does not analyze all calls from the constructor. for these, use definite assignment operator !. see #20166
3. RyanCavanaugh commented on Jan 10, 2018

   

   Ryan Cavanaugh (RyanCavanaugh)

   on Jan 10, 2018

   Member

   More actions

   See also long discussion of how this would be an expected effect #8476
4. berickson1 commented on Jan 11, 2018

   

   Brent Erickson (berickson1)

   on Jan 11, 2018

   Author

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   I understand that inheritance could make tracking calls from the constructor tricky if public methods were called.
   Has there been any thought regarding just tracking private method calls for variable initialization? We've done something similar to reset internal state of classes for unit testing. In this way we could do the following.

   export class Test {
       private _foo: string;
       constructor() {
           this._init(); //<- follow this chain
           this.myMethod();//<- don't follow this chain
       }
   
       private _init(override?: string) {
           this._foo = override || 'test';
       }
       
       public myMethod() {
           this._foo = 'bar'; // This isn't used to track strict property init
       }
   
       public resetState() {
           this._init('reset');
       }
   }
5. typescript-bot commented on Jan 25, 2018

   

   TypeScript Bot (typescript-bot)

   on Jan 25, 2018

   Contributor

   More actions

   Automatically closing this issue for housekeeping purposes. The issue labels indicate that it is unactionable at the moment or has already been addressed.
6. TypeScript Bot (typescript-bot)

   closed this as completedon Jan 25, 2018
7. microsoft

   locked and limited conversation to collaborators on Jul 3, 2018

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