You want to reopen the Hash class to add a method symbolize_keys that returns a new hash with all string keys converted to symbols. Which code correctly does this?
hard📝 Application Q15 of 15
Ruby - Class Methods and Variables
You want to reopen the Hash class to add a method symbolize_keys that returns a new hash with all string keys converted to symbols. Which code correctly does this?
Aclass Hash
def symbolize_keys
each_with_object({}) do |(k, v), h|
h[k.to_sym] = v
end
end
end
Bclass Hash
def symbolize_keys
map { |k, v| [k.to_sym, v] }
end
end
Cclass Hash
def symbolize_keys
keys.map(&:to_sym)
end
end
Dclass Hash
def symbolize_keys
self.transform_keys(&:to_sym)
end
end
Step-by-Step Solution
Solution:
Step 1: Understand the goal
We want a method that returns a new hash with string keys converted to symbols.
Step 2: Check each option's correctness
class Hash
def symbolize_keys
each_with_object({}) do |(k, v), h|
h[k.to_sym] = v
end
end
end manually builds a new hash but misses handling non-string keys safely. class Hash
def symbolize_keys
map { |k, v| [k.to_sym, v] }
end
end returns an array, not a hash. class Hash
def symbolize_keys
keys.map(&:to_sym)
end
end returns only keys as symbols, not a hash. class Hash
def symbolize_keys
self.transform_keys(&:to_sym)
end
end uses transform_keys(&:to_sym), a built-in method that correctly returns a new hash with symbol keys.
Final Answer:
class Hash
def symbolize_keys
self.transform_keys(&:to_sym)
end
end -> Option D
Quick Check:
Use transform_keys(&:to_sym) for symbol keys [OK]
Quick Trick:Use transform_keys(&:to_sym) to convert keys easily [OK]
Common Mistakes:
Returning array instead of hash
Not returning a new hash
Ignoring keys that are not strings
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