Proposal: Alternative public, private, static syntax and questions

Isiah Meadows isiahmeadows at gmail.com
Fri Jan 12 17:38:20 UTC 2018


I'd have to disagree. There are ways to spec around this, and as long
as you make explicit what you're inheriting, it's not as hard as you
might think.
-----

Isiah Meadows
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On Fri, Jan 12, 2018 at 6:15 AM, Naveen Chawla <naveen.chwl at gmail.com> wrote:
> Another problem with this.#myVar syntax is that it is not extensible to
> other access control definitions in future. For example "readonly" or
> "protected" etc.
>
> On Fri, 12 Jan 2018 at 05:12 Claude Petit <petc at webmail.us> wrote:
>>
>> I'm with you Isiah... Sorry, but all that to avoid "this." is laziness,
>> has no sense and add complexity to the language. Use a modern editor instead
>> of VI and you'll have auto-completion of that "so difficult to type" 4
>> letters word (this).
>>
>> -----Original Message-----
>> From: Isiah Meadows [mailto:isiahmeadows at gmail.com]
>> Sent: Thursday, January 11, 2018 5:26 PM
>> To: Naveen Chawla <naveen.chwl at gmail.com>
>> Cc: es-discuss at mozilla.org; Augusto Moura <augusto.borgesm at gmail.com>;
>> Brandon Andrews <warcraftthreeft at sbcglobal.net>
>> Subject: Re: Proposal: Alternative public, private, static syntax and
>> questions
>>
>> The proposal does a very poor job of explaining this, but `#foo` is a
>> shorthand for `this.#foo`, much like `{foo}` is a shorthand for `{foo:
>> foo}`. That kind of thing has precedent in other languages:
>> CoffeeScript uses `@foo` as a shorthand for `this.foo` (although it's not
>> private), and Ruby uses `@foo` as a shorthand for `self.foo` (which is
>> private by default). Most traditional strongly typed OO languages just let
>> you omit `this` and just reference the property as if it were a variable in
>> scope, without the sigil, and Ruby does as well for methods.
>>
>> It saves 5 characters in the most common case, accessing private
>> properties of the current instance.
>> -----
>>
>> Isiah Meadows
>> me at isiahmeadows.com
>>
>> Looking for web consulting? Or a new website?
>> Send me an email and we can get started.
>> www.isiahmeadows.com
>>
>>
>> On Thu, Jan 11, 2018 at 4:26 PM, Naveen Chawla <naveen.chwl at gmail.com>
>> wrote:
>> > I hadn't read the proposal properly, but the thrust of my point is the
>> > same, read remove/add `#` instead of "replace with this"
>> >
>> >
>> > On Fri, 12 Jan 2018, 2:47 am Naveen Chawla, <naveen.chwl at gmail.com>
>> > wrote:
>> >>
>> >> Massive drawback of the # semantic: making a private variable public
>> >> (a common transition when the usage of a class evolves) requires a
>> >> lot more refactoring, since you have to remove every # for the
>> >> variable across the class and replace it with `this`. Failing to do
>> >> so in just 1 instance creates a bug. The same drawback applies for
>> >> privatizing a public variable, in reverse.
>> >>
>> >> Besides which as an instance variable I want to learn `this` as the
>> >> access prefix. I don't want to have to learn 2 different access
>> >> prefixes, one for public and one for private. Access control in code
>> >> only has one real material advantage: simplifying the public
>> >> interface of a class by hiding factors that have no use from outside
>> >> it. This is not big enough of an advantage to introduce a new access
>> >> prefix, which can lead to a plethora of bugs due to confusion and/or
>> >> publicization/privatization transitions during the evolution of one's
>> >> system.
>> >>
>> >>
>> >> On Fri, 12 Jan 2018, 1:22 am Isiah Meadows, <isiahmeadows at gmail.com>
>> >> wrote:
>> >>>
>> >>> Inline
>> >>>
>> >>> -----
>> >>>
>> >>> Isiah Meadows
>> >>> me at isiahmeadows.com
>> >>>
>> >>> Looking for web consulting? Or a new website?
>> >>> Send me an email and we can get started.
>> >>> www.isiahmeadows.com
>> >>>
>> >>> On Thu, Jan 11, 2018 at 2:10 PM, Brandon Andrews
>> >>> <warcraftthreeft at sbcglobal.net> wrote:
>> >>> >
>> >>> > That is a very useful document. I guess I haven't opened the
>> >>> > proposal in a while.
>> >>> >
>> >>> >
>> >>> > He puts a lot of stress on preserving encapsulation where as I was
>> >>> > planning on relying on a type system to optionally provide that
>> >>> > feature.
>> >>> > That is given a dynamically typed variable accessing privates
>> >>> > would probably be allowed. (Statically typed variables would
>> >>> > detect and not allow that kind of like a more strict usage).
>> >>>
>> >>> The issue with leveraging static typing is that JS has never been a
>> >>> statically typed language. Also, private fields are generally
>> >>> something you shouldn't need static types to detect - even without
>> >>> the sigil, it *is* in fact possible to require something like
>> >>> `private foo` as a declaration and alter property lookup within
>> >>> classes to check for local private names (for class instances)
>> >>> before public ones. (Decided to create a GH issue out of this:
>> >>> https://github.com/tc39/proposal-class-fields/issues/69)
>> >>>
>> >>> > I think the inheritance and using private names as keys are decent
>> >>> > arguments. That said I'm personally not against allowing inherited
>> >>> > classes access to their base class private members though. That is
>> >>> > private acting like protected in C++ I think is fine for
>> >>> > ECMAScript. Am I alone in being fine with that behavior? I'm kind of
>> >>> > leaning toward:
>> >>> > https://github.com/tc39/proposal-private-fields/issues/14#issuecom
>> >>> > ment-216348883 that syntax for a true private class scope
>> >>> > variable.
>> >>>
>> >>> Note: not even Java allows subclasses to access superclasses'
>> >>> private fields.
>> >>>
>> >>> >
>> >>> > The key name conflict seems niche outside of key based data
>> >>> > structures.
>> >>> > I wrote an ORM system before and just used a key called "internal"
>> >>> > to hold data in the past to get around a similar conflict. The #
>> >>> > sounds like a similar workaround when required but allows
>> >>> > everything to not be hidden in a nested object which is nice.
>> >>> >
>> >>> > Are "protected" class fields a thing in this discussion at all? Or
>> >>> > is the idea to use or implement a friend system later somehow?
>> >>>
>> >>> See https://github.com/tc39/proposal-decorators/issues/25.
>> >>>
>> >>> >
>> >>> >
>> >>> > With how I use Javascript currently, and the direction I want
>> >>> > ECMAScript to head - toward types - I don't particularly like the
>> >>> > proposal or necessarily support its goals toward creating an ideal
>> >>> > encapsulation.
>> >>> > (Also I really dislike the syntax).
>> >>> > _______________________________________________
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>> >>> > es-discuss at mozilla.org
>> >>> > https://mail.mozilla.org/listinfo/es-discuss
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>>
>>
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