On 6/9/15 4:01 PM, Kevin Smith wrote:
how about introducing a well known concept in JS as `own` ?
```js
class Person {
static name String: "A person name"
own name String: "anonymous"
own items Array: []
Let's take a step back and ask: what's the motivation for having
these property declarations and initializers outside of the
constructor? As Mark pointed out, it's a syntactic feature that is
strictly less expressive than the current solution of putting property
assignments in the constructor body.
Instance property initializer syntax is really geared toward type
systems, where you are expressing type constraints (either structural
or nominal) on objects created by the given constructor.
Hmmm, this is really not the primary motivation of the proposal even if
it does dovetail nicely with what type systems need. The proposal grew
out of needs from real JS frameworks like React and Ember (see the
proposal slides again for references to how these frameworks wish to use
this).
Instead, the purpose of initializers outside of the constructor are to
increase expressivity in a different sense than what I think you meant
about constructor initialization: It allows initialization that isn't
based on logic in the constructor to be visually and clearly separate
from logic that is. It is strictly less expressive for
constructor-injected state patterns, but it is strictly more expressive
for other patterns of initialization.
I'm wary of adding syntax whose primary motivation is to express type
constraints, when we haven't even defined (or proposed) what typing in
JS means.
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