Cool idea! #2

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1. zackify commented on Aug 4, 2016

   

   zackify

   on Aug 4, 2016

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   That's funny, I just committed to a new branch that does the same mutable
   "hack" since you can't overload. I'll have to check yours out!
   On Thu, Aug 4, 2016 at 18:00 Boris Cherny notifications@github.com wrote:

   Hey there!

   I had a similar idea a while ago, but realized that without operator
   overloading this isn't a complete abstraction. Eg.

   import {Map} from 'immutable-proxy'
   const a = new Map({b: 1})a.b = 2assert(a.b == 2) // this just mutated a!

   If we had operator overloading, we could do this, though it feels strange
   in JS:

   import {Map} from 'immutable-proxy'
   const a = new Map({b: 1})const b = a.b = 2assert(a.b == 1)assert(b.b == 2)assert(a != b)

   Anyway, I ended up with this proof of concept:
   https://github.com/bcherny/auditable - mutable datatypes, backed by
   immutable data structures.

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2. kirillrogovoy commented on Sep 12, 2016

   

   kirillrogovoy

   on Sep 12, 2016

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   Hey guys! Wouldn't it be better just to deny in any direct set operations? I mean, this code should throw a TypeError: Direct data changes are prohibited, use .set()!

   import {Map} from 'immutable-proxy'
   
   const a = new Map({b: 1})
   a.b = 2
   

   const b = a.b = 2 feels very strange in JS and I bet it'd frighten most of users right away as it feels too much unnatural. However, a complete restriction of the set operations seems to be a rigid and, which is the most important`, a very practical way. All in all, the whole point of immutability is to put restrictions on the developer to avoid complexities and a whole subset of potential bugs.

   What do you think?

   👎React with 👎1Reacted by Dmytro Getmantsov
3. bcherny commented on Sep 12, 2016

   

   bcherny

   on Sep 12, 2016

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   const b = a.b = 2 feels very strange in JS

   I agree - that's why the abstraction is incomplete. Keep in mind that since JS does not have operator overloading, the above is actually impossible to implement without a macro or some other language extension.

   If you are OK with a less specific error message, you can implement your TypeError without Proxies:

   const map = Object.freeze(new Immutable.Map)
   map[2] = 3 // Error!
4. zackify commented on Sep 12, 2016

   

   zackify

   on Sep 12, 2016

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   That would actually be a good idea! I am up for changing it to throw an
   error.

   On Mon, Sep 12, 2016 at 1:44 PM Boris Cherny notifications@github.com
   wrote:

   const b = a.b = 2 feels very strange in JS

   I agree - that's why the abstraction is incomplete. Keep in mind that
   since JS does not have operator overloading, the above is actually
   impossible to implement without a macro or some other language extension.

   If you are OK with a less specific error message, you can implement your
   TypeError without Proxies:

   const map = Object.freeze(new Immutable.Map)
   map[2] = 3 // Error!

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