Photo by Caroline Attwood on Unsplash.
What's wrong with this code?
Can you find the logical error?
(⚠️ As the tag shows, it's a non-sensical/fun question)
const { flour, eggs, turkey } = groceries
Answer
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.
.
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.
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You can't cook ingredients (as they are constant thus can't cook them) and have to eat'em raw 😛.
Background Story.
I was chatting with other developers and wanted to make sure if he understood JavaScript Object Destructuring concept correctly.
let { flour, eggs, turkey } = groceries
Someone suggested const
instead of let
promoting a better coding style.
And the first thing popped in my mind was that you can't eat a raw 🦃.
👋 Parting Words
Hope it funny enough 😎.
Top comments (24)
The reason to use
const
instead oflet
is because you want your code to be immutable. (just a note,const
doesn't make object immutable, you have tofreeze
).So how do you eat your groceries while being immutable?
Try to view immutable code as code with the added dimension of TIME!
At any moment in our application we can go back and look at what the state was before.
So imagine at 12:00 you had raw turkey. then at 12:30 you had cooked turkey. This is how immutable code works.
With mutable code, you know you have cooked turkey, but your past is invisible to you. You can never look at a previous state.
Thanks joelnet for following up with technical aspect of the code and the implication of using
const
.const is a good practice, but you even continue using let with immutable code. Sometimes it’s easier and more readable to use let for an immutable object, to which you are going to apply transforms.
sure.
i just try my best to make everything immutable and handle mutable state separately, like in a redux store.
@joelnet I still don't need
cookTurkey
instead I can doturkey.cooked = true
and so it doesn't matter whether I useconst
orlet
if my code is written keeping immutability in mind.that is kind of why I mentioned '(just a note, const doesn't make object immutable, you have to freeze)' was to distinguish between const and immutable.
If you want a primitive value to be immutable,
const
is enough. If you want an object to be immutable, you have to freeze it as well.So if we can assume
groceries
is immutable (which is should be).Then your groceries will truly be immutable
Sorry. Misunderstood as the freeze wasn't mentioned in the previous code. Thanks for clearing it up! :)
const
. I hateconst
in Javascript, because it's notconst
at all - butfinal
. In Kotlin, this'd beval
instead ofvar
- but even then, this is a fixed binding, and not an invariant.So you can cook the turkey, for sure, you just can't change which turkey you're cooking.
In C++, on the other hand,
const Turkey turkey
means an invariant Turkey.const Turkey * turkey
means a pointer to a constant Turkey. In either case, you couldn't callTurkey::cook()
, but you could callTurkey::price() const
, since that's a const method. But in the latter case, you could assign (or "rebind")turkey
to point at a different instance. To prevent that, we can sayconst Turkey * const turkey
, which is getting to be a mouthful. C++ also has references, which are non-rebindable pointers with easier syntax:const Turkey & turkey
is equivalent to that last double-const pointer example.All these headaches might be a good reason to learn Functional Programming... 🤔
And now I'm reminded why I prefer to code in Python or JS. Listening to the C++ version hurts my brain. A fragile Front-End guy and I'm thankful to not be doing C++
Thanks Nick.
After reading your comment, I dug around and found this StackOverflow answer, which also explained using an example.
I wasn't aware that
nested object
could be modified even after being frozen.Not really, the "turkey" is a pointer to the turkey instance/value, so even if the turkey changes its state, the turkey pointer will remain constant, pointing to the same turkey.
I had this imagination that, the 🦃 looks the same on the outside but cooked on the inside 😃.
haha, it sounds reasonable :D
Still not edible, take it back for a re-rest 😂
You forgot a semicolon at the end.
I've been waiting for someone to point that out as well 🤣
This is an interesting point. What if some of the groceries where constant, such as the old tins you'll have in your cupboard for years. Seriously though, you can only have all constant or all let.
Thanks Adam, you are right, I've realized that the syntax is for
all || nothing
Came for the fun, stayed for the conversation. Love all the comments!
Yupz, it's awesome how you learn from different perspectives and finding out faults so we could all learn 😀
Oh another thing, your destructuring references could be alphabetical.
🤣
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