Le 27/12/2011 19:14, Mark S. Miller a écrit : > On Tue, Dec 27, 2011 at 7:15 AM, David Bruant <[email protected] > <mailto:[email protected]>> wrote: > > Hi, > > Maps [1] and WeakMaps [2] are very similar in their API. Since neither > proposal discusses how they should interact with each other, I was > wondering what is supposed to happen when trying to use the API of one > on the other. > ----- > var m = new Map(); > var key = {}; > m.set(key, 37); > > WeakMap.prototype.get.call(m, key); // ? > ----- > > Currently Chrome canary says "illegal access". > Is it the behavior that is wished for the features? > > > That's what I wish. JS already has name-based polymorphism (as is > typical of scripting languages). Generic methods, such as those from > Array.prototype, are only appropriate when the actions of the generic > method can itself be fully described in terms of accessing other > publicly available properties by name-based lookup. In this case, > get/set/has/delete is the lowest level publicly available interface, > and their semantics is defined in terms of accessing internal > encapsulated properties. In this regard, they are more like the > Date.prototype methods. The fact that similar operations have the same > names is all the polymorphism these need or should have. Very interesting point.
Currently, the Date.prototype method throw a TypeError (ES5.1 - 15.9.5 introductory section). The same is probably expected when trying map operations on weakmap (etc.) ? David
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