`<main>': undefined method `call' for nil:NilClass (NoMethodError)-CodePudding

I am currently self teaching Ruby and am practicing methods. So, I just don't seem to understand why my console continuously prints out a error message after the proper conditional is printed. Any explanation would be appreciated!

def test(tester)
    if tester
        puts "yes";
        
    else
        puts "error";
    end
end

#call function
test(:tester).("hello world");

Output:

yes
main.rb:10:in `<main>': undefined method `call' for nil:NilClass (NoMethodError)

Why am I getting this error??

CodePudding user response：

foo.(bar) is syntactic sugar for foo.call(bar). So, test(:tester).("hello world") is syntactic sugar for test(:tester).call("hello world").

However, test returns nil, so you are calling nil.("hello world") which is the same as nil.call("hello world"), and if you look at the documentation of NilClass, you can easily see that it does not have a method named call. (NilClass inherits from Object which in turn inherits from Kernel and BasicObject, so theoretically, the method could be defined there, but as you can easily check yourself, it isn't.)

Since you are calling a method that does not exist, you get a NoMethodError.