I’m going to see what compiler changes are needed for this. -Alex
On 9/18/15, 4:56 PM, "Josh Tynjala" <joshtynj...@gmail.com> wrote: >Here's the section on reserved words in the ES5.1 spec: > >http://www.ecma-international.org/ecma-262/5.1/#sec-7.6.1 > >And the same section in the ES6 / ES2015 spec: > >http://www.ecma-international.org/ecma-262/6.0/#sec-reserved-words > >The rule seems to hinge on whether something is an "identifier" or an >"identifier name". It says that an "identifier" is any valid "identifier >name", not including reserved words. > >I'm not an expert at reading language specs, so I can't find the places >where the spec clearly shows that an "identifier name" is allowed. > >Mozilla's docs have a clearer explanation, though. >https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Lexical_ >grammar#Keywords > >Basically, in JS, it seems to boil down to places where you're allowed to >optionally put quotes around something: > >1. obj.identifierName > >2. obj.indentifierName() > >3. { identifierName: 2 } > >They could all be rewritten with quotes: > >1. obj["identifierName"] > >2. obj["indentifierName"] > >3. { "identifierName": 2 } > >The Mozilla doc notes that this is not allowed, though: > >function identifierName() {} //error > >At first, I noticed similarity to member functions in AS3: > >class MyClass >{ > public function identifierName() {} //is this considered the same as >above? >} > >However, the first one could be rewritten like this, where it's a >variable, >which must be an "identifier" instead of an "identifier name": > >var identifierName = function() {} //error because identifier names are >not >allowed! > >If classes are considered syntactic sugar for prototypes, then the AS3 >version might be considered to be equivalent to this: > >MyClass.prototype.identifierName = function() {} > >We can rewrite that one with quotes, so the original sugar seems safe as >an >"identifier name", assuming that AS3 should follow the same logic. > >MyClass.prototype["identifierName"] = function() {} > >Anyway, just trying to wrap my head around it all. > >- Josh > >On Fri, Sep 18, 2015 at 2:03 PM, Alex Harui <aha...@adobe.com> wrote: > >> Josh, >> >> The key question here is whether is it is not valid AS3 per the language >> spec, or whether the runtime and/or the compiler won’t let you compile >>it. >> >> AFAICT, what you want to do here is valid AS3 and I would expect the >> runtime to run the expected ABC code, so it should be possible to get >>the >> compiler to allow it. Where to look in the compiler code, I’m not sure. >> My trick is to set a breakpoint on the CompilerProblem constructors and >> look up the stack to see who decided it was time to generate an error >>and >> why. >> >> One more scenario that I ran into today and haven’t tested on JS: >> >> I was porting the MXML feature test base class and to create AS feature >> tests. It had: >> var mxml:String = generateMXMLForTest(); >> >> Which I changed to: >> var as:String = generateASForTest(); >> >> I would expect this to be valid in JS because “as” is not a keyword in >>JS. >> It is interesting that you can’t do “var var” in JS or AS3, but since >>AS3 >> has more keywords like that than JS, it is possible someone might have a >> d.ts file with an API with an AS-only keyword in it and then I’m not >>sure >> what to do there. In this case, though, I think it should be ok to >>have a >> local variable names “as”. >> >> So, do we know in JS where keywords are and aren’t allowed? >> >> Can you do: >> var in; >> >> Or: >> >> foo = function(in, out) >> >> We should probably get the big picture of where keywords are allowed >> before making changes in this area. >> >> Thanks, >> -Alex >> >> >> On 9/18/15, 12:39 PM, "Josh Tynjala" <joshtynj...@gmail.com> wrote: >> >> >JavaScript allows the use of reserved words as members of >> >classes/interfaces, but AS3 does not. >> > >> >In JS and AS3, this is not valid: >> > >> >var var = 5; >> > >> >However, in JS, this is valid: >> > >> >var obj = {}; >> >obj.var = 5; >> > >> >Not in AS3, though. >> > >> >Similarly, these are not valid AS3, but some JS types have methods with >> >these exact names, so that needs to change: >> > >> >class Test >> >{ >> > public function delete():void {} >> > public function continue():void {} >> >} >> > >> >As far as I can tell, this JS behavior became valid in ES5. I assume >>after >> >ES4 was cancelled. There are even some APIs in the JS standard library >> >take >> >advantage of this behavior already, and I'm sure that many JS >>libraries do >> >too. >> > >> >Right now, to successfully build a standard library with externc (or my >> >dts2as tool), these APIs need to be completely excluded. It's fine for >>a >> >temporary workaround, but it will become an issue eventually. >> > >> >Alex, since you've been talking about compiler changes, I thought I'd >> >throw >> >this one into the ring too. >> > >> >(I'm not yet familiar with this part of the compiler, but if I knew >>where >> >to look, I might be able to figure it out.) >> > >> >- Josh >> >>
