Proposal: Alternative public, private, static syntax and questions

Naveen Chawla naveen.chwl at gmail.com
Thu Jan 11 21:17:05 UTC 2018


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
>
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> Isiah Meadows
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> 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#issuecomment-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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