CODEWITHSUNDEEP
rubyruby-on-rails-3.1
Pykih
Pykih

Reputation: 2827

Method Parameters to String

1) I have a method 

def self.createobj(api_key, amnt, commentstr, orderid, order_creation_date, orderfullfilmentdate)  
.....
end

2) I want to create a error_str of all the parameters passed to this function ...

2.1) Something like 

errorstr = "api_key: " + api_key.to_s + " amnt: " + amnt.to_s + " commentstr: " + commentstr.to_s + " orderid: " + orderid.to_s + " order_creation_date: " + order_creation_date.to_s + " orderfullfilmentdate: " + orderfullfilmentdate.to_s

2.2) So I created another method

def self.get_params_str(a)
    str = ""
    a.each do |a|
      str = str + a.to_s
    end
    return str
end

2.3) So I call this new method from createobj. Something like 

def self.createobj(api_key, amnt, commentstr, orderid, order_creation_date, orderfullfilmentdate)  
errorstr = get_params_str(args)
.....
end

3) But I get error undefined local variable or method `args' for #. Shouldn't args have all parameters?

Please advice.

Upvotes: 0

Views: 2011

Answers (3)

derp
derp

Reputation: 3020

As stated in the other responses there's no available variable like args that provides the names of the arguments for the method, however if you're on Ruby 1.9.2 (I can't confirm if exist on 1.9.1 as well) you have the method parameters so you can do something like this:

def foo(a, b, c)
    errorstr = method(:foo).parameters.map{|p| "#{p.last}: #{eval p.last.to_s}" }.join(', ')
    puts errorstr
end

foo(1, 2, 3) #=> a: 1, b: 2, c: 3

Upvotes: 1

Larry K
Larry K

Reputation: 49104

What you're trying to do (trying to use a magic var called args that will hold all of the arguments) doesn't work in this way in Ruby.

A method can have optional args:

def my_method(*args)
  ....
  # the array args will have 0 or more elements, depending on how many
  # were in the method invocation.
end

But if a method has specific (required) args, as in your example, then there is no other way to get at them.

Added If you're willing to change the definition of your method to use the work-around for named arguments, then the args will arrive as an associative array and you can then send them to your get_params_string

Or better, redefine your get_params_string to take a variable arg list

def self.get_params_str(*a)
  str = ""
  a.each do |a|
    str = str + a.to_s
  end
  return str
end  

# Then call it from your main method:
def self.createobj(api_key, amnt, commentstr, orderid, 
                   order_creation_date, orderfullfilmentdate)  
  errorstr = get_params_str(api_key, amnt, commentstr, orderid, 
                   order_creation_date, orderfullfilmentdate)
  .....
end

See a useful post

Upvotes: 2

Carl Zulauf
Carl Zulauf

Reputation: 39558

args would only contain the parameters if your method definition was something like def self.createobj(*args). Without that args isn't defined.

You will need to manually pass all of the parameters to get_params_str. You will need to pass them as an array, i.e get_params_str([api_key, amnt, commentstr, ...]) unless you change get_params_str's method signature to def self.get_params_str(*a) (which puts all of the parameters passed to get_params_str into a single array`).

Upvotes: 1

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