Catch doubly defined inputs & outputs

[MichaelRFairhurst]

For example

  <div [innerHtml]="blah" [innerHtml]="blah"></div>

and

  <div (click)="blah" (click)="blah"></div>

and even

  <input [(ngModel)]="blah" [ngModel]="blah" (ngModelChange)="blah" />

All should be errors. Probably best to highlight both as errors though we could highlight just the second one

[zoechi]

I assume this is only if the expression (blah) is also exactly the same?

[MichaelRFairhurst]

Ah yes... (click)="x" (click)="y" is the same as (click)="x; y" which is totally valid, so this is a stylistic choice not an error. Granted, I'm not sure if the order of the former is deterministic and it may therefore be a code smell.

But even then, a great example is [(ngModel)]="x" (ngModelChange)="y" which also might not have a deterministic order but is absolutely reasonable; you want to have a two way binding and two listen to it (perhaps because you have a chain of two way bindings). Granted, desugaring the ngModel is possible and leads to a deterministic order.

Of course for inputs the restriction still applies.

@matanlurey any thoughts on the deterministic ordering of repeated event tags?

On Dec 30, 2016 3:20 AM, "Günter Zöchbauer" [email protected] wrote:

I assume this is only if the expression (blah) is also exactly the same?

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[zoechi]

I saw it mentionen in TS GitHub issues several times that order of event handlers is explicitely not defined. Curious whether this is the same in Dart.

[MichaelRFairhurst]

This is currently caught because its an html parse error. Still, I'll leave this in, because we will soon be switching to a parser which may not catch this.