[ruby] What does "wrong number of arguments (1 for 0)" mean in Ruby?

What does "Argument Error: wrong number of arguments (1 for 0)" mean?

I assume you called a function with an argument which was defined without taking any.

def f()
  puts "hello world"
end

f(1)   # <= wrong number of arguments (1 for 0)

You passed an argument to a function which didn't take any. For example:

def takes_no_arguments
end

takes_no_arguments 1
# ArgumentError: wrong number of arguments (1 for 0)

If you change from using a lambda with one argument to a function with one argument, you will get this error.

For example:

You had:

foobar = lambda do |baz|
  puts baz
end

and you changed the definition to

def foobar(baz)
  puts baz
end

And you left your invocation as:

foobar.call(baz)

And then you got the message

ArgumentError: wrong number of arguments (0 for 1)

when you really meant:

foobar(baz)