Renaming in destructuring

[ehpc]

I want to disagree with you about renaming kata http://tddbin.com/#?kata=es6/language/destructuring/rename. I think there is no renaming. Let me explain my point of view.

We have this code [1]:
const {x: y} = {x: 1};
assert.equal(y, 1);

It is equivalent to [2]:
const {x: x} = {x: 1};
assert.equal(x, 1);

Which is in turn equivalent to [3]:
const {x} = {x: 1};
assert.equal(x, 1);

So in snippet 3 we have a case of shorthanding the destructuring assignment. Basically it means: destructure an object which has a property by the name "x" and assign it's value to a variable named "x". The explicit version of this is in snippet 2.
Snippet 1 on the other hand tells: destructure an object which has a property by the name "x" and assign it's value to a variable named "y".
There is no renaming of any kind, just a classical destructuring.

We can see this in specs: http://www.ecma-international.org/ecma-262/6.0/#sec-destructuring-assignment. The grammar reads as follows:
AssignmentProperty[Yield] :
IdentifierReference[?Yield] Initializer[In,?Yield]opt
PropertyName : AssignmentElement[?Yield]
AssignmentElement[Yield] :
DestructuringAssignmentTarget[?Yield] Initializer[In,?Yield]opt

So we have a "PropertyName" and an "AssignmentElement", which is no more than a "DestructuringAssignmentTarget" with an optional "Initializer".
In out example:

const {
x: // PropertyName
y // DestructuringAssignmentTarget
} = {x: 1};

or even:

const {
x: // PropertyName
y // DestructuringAssignmentTarget
=42 // Initializer
} = {y: 23};

The word "rename" might not be the best, I agree. Reassign or alike might
be better fits.
Am 27.07.2015 8:22 nachm. schrieb "Eugene Maslovich" <
notifications@github.com>:

I want to disagree with you about renaming kata
http://tddbin.com/#?kata=es6/language/destructuring/rename. I think there
is no renaming. Let me explain my point of view.

We have this code [1]:
const {x: y} = {x: 1};
assert.equal(y, 1);

It is equivalent to [2]:
const {x: x} = {x: 1};
assert.equal(x, 1);

Which is in turn equivalent to [3]:
const {x} = {x: 1};
assert.equal(x, 1);

So in snippet 3 we have a case of shorthanding the destructuring
assignment. Basically it means: destructure an object which has a property
by the name "x" and assign it's value to a variable named "x". The explicit
version of this is in snippet 2.
Snippet 1 on the other hand tells: destructure an object which has a
property by the name "x" and assign it's value to a variable named "y".
There is no renaming of any kind, just a classical destructuring.

We can see this in specs:
http://www.ecma-international.org/ecma-262/6.0/#sec-destructuring-assignment.
The grammar reads as follows:
AssignmentProperty[Yield] :
IdentifierReference[?Yield] Initializer[In,?Yield]opt
PropertyName : AssignmentElement[?Yield]
AssignmentElement[Yield] :
DestructuringAssignmentTarget[?Yield] Initializer[In,?Yield]opt

So we have a "PropertyName" and an "AssignmentElement", which is no more
than a "DestructuringAssignmentTarget" with an optional "Initializer".
In out example:

const {
x: // PropertyName
y // DestructuringAssignmentTarget
} = {x: 1};

or even:

const {
x: // PropertyName
y // DestructuringAssignmentTarget
=42 // Initializer
} = {y: 23};

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#15.

[ehpc]

Well I think reassign doesn't cut it either. We can see how destructuring is described in Clojure for example: http://clojure.org/special_forms, especially map binding destructuring. So basically the thing to the left of assignment operator in js code is binding form and the thing to the right is initialization expression. There is no reassignment, there is only an "assignment" of symbols from the left part of expression (would be variables) to parts of an object from the right part. So symbol "y" is bound to value of a property "x". No renaming, no reassignment, just plain straight name binding. Hope this makes sense.

Right assigning would be the right thing then. Just don't know how to make
it work so it doesn't break bc for all links etc.
Am 27.07.2015 9:34 nachm. schrieb "Eugene Maslovich" <
notifications@github.com>:

Well I think reassign doesn't cut it either. We can see how destructuring
is described in Clojure for example: http://clojure.org/special_forms,
especially map binding destructuring. So basically the thing to the left of
assignment operator in js code is binding form and the thing to the right
is initialization expression. There is no reassignment, there is only an
"assignment" of symbols from the left part of expression (would be
variables) to parts of an object from the right part. So symbol "y" is
bound to value of a property "x". No renaming, no reassignment, just plain
straight name binding. Hope this makes sense.

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#15 (comment).