CODEWITHSUNDEEP
ruby-on-railsruby
Sarangan Rajamanickam
Sarangan Rajamanickam

Reputation: 63

Ruby Argument Error with named parameter

Consider the following Ruby Code:

def f1(p1, p2: nil, p3: nil)
  puts "Parameter 1: #{p1}"
  puts "Parameter 2: #{p2}"
  puts "Parameter 3: #{p3}"
end

def f2(p1, p2: nil, p3: nil)
  f1(p1, p2, p3)   
end

# This will throw error ArgumentError: wrong number of arguments (3 for 1)
f2("Hi")

In the above code, my problem is I need to list the parameters in both f1 and f2 (user requirement). At the same time I should enable the named parameters for the user (because the 3 parameters can become 30 parameters with most of them having a default value)

Has anyone come across this issue?

Upvotes: 2

Views: 451

Answers (1)

Nermin
Nermin

Reputation: 6100

You used named parameters, you have to specify them explicitly.

...
def f2(p1, p2: nil, p3: nil)
  f1(p1, p2: p2, p3: p3)   # specify p2 and p3
end

f2("Hi")

When you call f1 you have to specify explicitly p2 and p3 if you want to define them

Check the official documentation or some third-party resources about this

def foo(arg1 = 1, arg2:, arg3: nil)
   puts "#{arg1} #{arg2} #{arg3}"
end

foo(arg2: 'arg2')
# Will display
# 1 arg2

foo('arg1_defined', arg2: 'arg2')
# WIll display
# arg1_defined arg2

Note: Also named arguments do not have to follow order, you can place them at any order you want, but after other arguments

foo(arg3: 'arg3_with_value', arg2: 'arg2_val')
# 1 arg2_val arg3_with_value

foo(arg3: 'arg3_val', 10)
# SyntaxError: unexpected ')', expecting =>
# they have to be after not-named arguments

Upvotes: 4

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