"reflection support could be opt-in (or opt-out)"
On reflection (pun unintended) maybe that is not sensible, given it is
baked in to the framework classes. If GCC does dead-code elimination, maybe
that does the job anyhow.
On Thu, Sep 29, 2016 at 7:02 AM, Greg Dove <greg.d...@gmail.com> wrote:
> Alex, I had also considered the same idea of doing the qualifiedName
> splitting in the reflection data because I think you would reduce a lot of
> long string variation in the GCC release build simply by doing
> 'org.apache.flex.'+'Package.'+'ClassName' etc
>
> Isn't using the reflection member definition names for access also another
> use that would qualify as 'dynamic' access? I am not sure if GCC can make
> the connection between the reflection data field names and the original
> naming of the fields which is why we need @export on instance members and
> @expose on static members (without those it fails iirc).
>
> One option for the future might be to make Reflection support optional. I
> think we might still want FLEXJS_CLASS_INFO, but perhaps the rest of the
> the reflection support could be opt-in (or opt-out). This alone could
> reduce a lot of code for people who don't need that.
>
>
>
>
> On Thu, Sep 29, 2016 at 6:17 AM, Alex Harui <aha...@adobe.com> wrote:
>
>>
>>
>> On 9/28/16, 3:25 AM, "Harbs" <harbs.li...@gmail.com> wrote:
>>
>> >I like this idea and would propose taking it one step further:
>> >
>> >Currently transpiled javascript has fully qualified class names for
>> >pretty much everything. This is difficult for closure to minimize
>> >completely. I’d really like to have some way to “export” class names as
>> >well as “import” to define some compact name for packages. Based on my
>> >playing around, this could save at least tens of KB of JS downloads.
>>
>> For sure, the amount of download for strings is a significant waste of
>> bytes in most cases. However, I'm not sure we need to provide renaming
>> controls for folks building FlexJS apps, at least not for the mainstream.
>>
>> AIUI, every public property and method in FlexJS is "exported" to prevent
>> renaming for a few "just-in-case" reasons. First, a review of renaming:
>>
>> FlexJS uses the Google Closure Compiler to optimize/minify the output JS
>> file. In doing so, GCC tries to renaming variables. For example, every
>> FlexJS class has a FLEXJS_CLASS_INFO property on it. Google might rename
>> that property to just "a", so the original JS might look like:
>>
>> UIBase.prototype.FLEXJS_CLASS_INFO = {..};
>>
>> But GCC will cause that to look like:
>>
>> UIBase.prototype.a = {..};
>>
>> If you replace "FLEXJS_CLASS_INFO" with "a" in every FlexJS class, you can
>> save quite a bit of download size. But then, what happens if someone
>> writes code that looks like:
>>
>> var foo:Object = someUIBase.FLEXJS_CLASS_INFO;
>> var bar:Object = someUIBase["FLEXJS_CLASS_INFO"];
>>
>> For the first line, GCC will know to alter the code to look like:
>>
>> var foo:Object = someUIBase.a;
>>
>> And everything will work fine, but AIUI, GCC does not try to alter strings
>> so it will not touch the "bar" code and that would fail at runtime since
>> there is no longer a property called "FLEXJS_CLASS_INFO" on UIBase.
>>
>>
>> But I think that GCC is now smart enough that if you actually have a line
>> like the "bar" line, that will prevent GCC from renaming
>> FLEXJS_CLASS_INFO. GCC might make an alias instead. GCC knows that the
>> output must have the bytes for "FLEXJS_CLASS_INFO" once in order to honor
>> the string literal, so it will create an alias like aa =
>> "FLEXJS_CLASS_INFO" and then the code is output as:
>>
>> UIBase.prototype[aa] = {..};
>> And
>> var foo:Object = someUIBase[aa];
>> var bar:Object = someUIBase[aa];
>>
>> IOW, GCC has a pretty good alias generator, which is why I don't think our
>> tool chain needs to provide folks with the manual options to rename. We
>> should just let GCC do its thing.
>>
>>
>> So, AIUI, the reason we export every public thing isn't for the standard
>> dynamic access case as shown above, but for two others (and related
>> scenarios):
>> -Dynamic access using generated strings
>> -Binding expressions with "dot-paths"
>>
>> Dynamic access using generated strings are scenarios where you know that
>> every property starts with "str_" and run code like:
>>
>> var foo:String = bar["str_" + i];
>>
>> GCC isn't smart enough to handle this.
>>
>> Dot-path Binding Expressions are where you want to use data binding to
>> bind to "myModel.subObject.someProperty". GCC will just look at the
>> entire string and since it doesn't match any property it will rename
>> myModel and subObject and someProperty and the binding will fail at
>> runtime.
>>
>> So, AIUI, we have huge string tables in our apps for these two cases even
>> though 99% or even 100% of the time, your app isn't going to access those
>> methods and properties in a way that GCC can't detect. So, before we add
>> some user-controlled renaming, I think we should first explore a compiler
>> option like -no-rename where you guarantee that your app doesn't use
>> generated strings or dot-path binding expressions and we clear all the
>> @exports out of the code before sending it to GCC.
>>
>> I'll bet somewhere in the framework we do use generated strings and will
>> have to fix that up, but I think that should be doable. I think the
>> compiler could also output string literals with "." in them as separate
>> strings and that might solve the dot-path problem. IOW, instead of simply
>> outputting "myModel.subObject.someProperty", the compiler would output:
>>
>> "myModel" + "." + "subObject" + "." + "someProperty"
>>
>> I've also seen information that indicates we might be able to control or
>> provide hints to GCC about what it can rename such that a smarter FalconJX
>> could look for dynamic access and tell GCC not to rename properties in
>> classes it knows will be dynamically accesses and let GCC rename
>> everything else.
>>
>> Volunteers are welcome to do more research on leveraging and controlling
>> GCC renaming. I haven't made it a high priority for me.
>>
>> My 2 cents,
>> -Alex
>>
>>
>
