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56 lines
1.3 KiB
Markdown
56 lines
1.3 KiB
Markdown
# Gather Positional Arguments In Method Definition
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The `*` symbol can be used in Ruby in a method definition to gather up an
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arbitrary number of positional arguments.
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For instance, we can gather all positional arguments with this method
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definition:
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```ruby
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def gather_all(*args)
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puts args
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end
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```
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Or we can isolate the first positional arg and then gather the rest:
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```ruby
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def first_and_rest(first, *rest)
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puts "First: #{first}, Rest: #{rest}"
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end
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```
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We can even do something a bit more interesting like isolating the first and
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last arguments while gathering up everything else in the middle:
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```ruby
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def pop_parens(left, *middle, right)
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if left != '(' || right != ')'
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raise "Uh oh!"
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else
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if middle.size == 1
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puts "Found: #{middle.first}"
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else
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pop_parens(*middle)
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end
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end
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end
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```
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Here is what it looks like if we splat some different sets of arguments into
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that method call:
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```ruby
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> tokens1 = "((((4))))".split('')
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=> ["(", "(", "(", "(", "4", ")", ")", ")", ")"]
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> tokens2 = "((4))))".split('')
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=> ["(", "(", "4", ")", ")", ")", ")"]
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> pop_parens(*tokens1)
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Found: 4
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=> nil
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> pop_parens(*tokens2)
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(irb):87:in `pop_parens': Uh oh! (RuntimeError)
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```
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[source](https://ruby-doc.org/3.3.6/syntax/methods_rdoc.html#label-Array-2FHash+Argument)
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