Proposing new warning

[Miguel A Salinas II]

Hi all,
I’m wondering where to pitch an idea and implementation of a new warning. I found that new ruby programmers get confused between strings and symbols especially when using them as keys in hashes. I made a small change that warns when there is a value in the hash with a symbol as its key but you are trying to access it with the equivalent string. E.g.
hash = {this: “that”}
puts hash[“this”]

Warning: no value stored for key “this”. Value found for equivalent symbol key :this. Did you mean to use a symbol?

Any pointers for how to propose this would be greatly appreciated. Thanks!

- miguel

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[Victor Shepelev]

You can use an official bug/proposal tracker: https://bugs.ruby-lang.org/
(it is open for anybody).

About your proposal: I like the friendliness, but I am afraid there would
be performance implications, probably.

Post by Miguel A Salinas II
Hi all,
I’m wondering where to pitch an idea and implementation of a new warning.
I found that new ruby programmers get confused between strings and symbols
especially when using them as keys in hashes. I made a small change that
warns when there is a value in the hash with a symbol as its key but you
are trying to access it with the equivalent string. E.g.
hash = {this: “that”}
puts hash[“this”]
Warning: no value stored for key “this”. Value found for equivalent symbol
key :this. Did you mean to use a symbol?
Any pointers for how to propose this would be greatly appreciated. Thanks!
- miguel
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[Greg Navis]

Also, existing apps may start generating lots of warnings. What if I store
both string and symbols in a hash?

Best
Greg

[Walter Lee Davis]

I would trigger the warning only after a key miss, so the overhead would only happen in case of a completely missing key. So if you had { foo: 'bar', 'foo' => 'baz', 'boo' => 'blarg' } and you asked for test['foo'] and test[:foo], you would get bar and baz, but if you asked for test[:boo], you would get the warning.

Walter

Also, existing apps may start generating lots of warnings. What if I store both string and symbols in a hash?
Best
Greg
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[Ale Miralles]

"What if I store both string and symbols in a hash?"
If I were doing that, I would appreciate a warning.

~ Ale Miralles.
https://medium/amiralles
http://amiralles.com.ar

Post by Greg Navis
Also, existing apps may start generating lots of warnings. What if I store
both string and symbols in a hash?
Best
Greg
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[Hassan Schroeder]

Post by Ale Miralles
"What if I store both string and symbols in a hash?"
If I were doing that, I would appreciate a warning.

I'm not sure I understand why -- *any* object can be a Hash key, not
only strings or symbols.

If I had a use case for requiring keys to be the same type I would
probably either subclass Hash or rely on a linter like RuboCop.

[Dan Fitzpatrick]

I prefer the monkey patch to Hash in this case. String/Symbol keys on
hashes is one of the only thinks I don't like about Ruby. So I "divide"
my hashes by key with the "/" function:

Add this:

class Hash
def /(k)
self[k.to_sym] || self[k.to_s]
end
end

Then you can do this:

h1 = {a: 1, b: 2}
h2 = {"c" => 1, "d" => 2}

The following returns 1:

h1/:a # 1
h2/:c # 1

x = 'a'
h1/x # 1

One issue is if you append another function you have to use parenthesis:

h = {now: Time.now}
h/:now.strftime('%Y%m%d') #<= ERROR
(h/:now).strftime('%Y%m%d') # "20181023"

This is my solution but it is considered hackery by many. The thing I
like about it is that it is easy and I know that I am getting values by
symbol or key and you can still do stuff like:

h = {a: 1, "a" => 2} and access the values as you normally would with
h[:a] or h["a"]


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[Andy Jones]

Post by Hassan Schroeder
If I had a use case for requiring keys to be the same type I would
probably either subclass Hash or rely on a linter like RuboCop.

I thought that subclassing the basic collection classes like Hash or Array was a bad idea? Because under the hood, their implementation was optimised, and it could lead to unforeseen effects?

Of course, you can always use composition instead of inheritance.


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[Greg Navis]

I personally wouldn't like to see a warning like that as there are simple
methods of addressing such confusion.