On Jan 30, 2014, at 8:49 AM, Domenic Denicola wrote: > From: Allen Wirfs-Brock <[email protected]> > >> If you invert things you can think of "invalid operation" as trying to apply >> a valid operation upon the "wrong kind of object" so TypeError is a >> plausible. > > This seems like a stretch :P. Are there existing instances in the ES spec of > this kind of use? I guess maybe trying to write to a non-writable property in > strict mode and the like.
Sure, all over the place. For example, trying to apply a built-in constructor to an object that doesn't have the expected set of internal slots. > >> In practice, where would throwing OperationError instead of TypeError >> actually make any difference. How would you handle one differently from the >> other? > > In practice it makes almost no difference, just like all other ECMAScript > error type discrimination. It just seems that when a user sees `TypeError` in > a stack trace, they expect to find some kind of argument validation problem. > > (Maybe once we get pattern-matching `catch` clauses it would matter more. > E.g. people could purposefully try to catch `OperationError`s from such > operations, and handle them differently, leaving `TypeError`s etc. to bubble > outward and hit a top-level exception handler as "truly unexpected." But > that's a ways off.) > > --- > > Sounds like `TypeError` is probably the way to go, even if it feels a bit off. We work with the tools that are available... > _______________________________________________ es-discuss mailing list [email protected] https://mail.mozilla.org/listinfo/es-discuss
