newb questions

[junji]

i was trying the tutorials for ruby and they gave this code it seems to
have an error well anyway this is the code so whats wrong with it

class Song2
attr_reader :name, :artist, :duration
end
aSong = Song2.new("Bicylops", "Fleck", 260)
aSong.artist #» "Fleck"
aSong.name #» "Bicylops"
aSong.duration #» 260


can anyone tell me whats wrong here

this is what the error looks like
....4:in `initialize': wrong number of arguments (3 for 0)
(ArgumentError)
from F:/junji/ruby-study/class/song2.rb:4

Thanks all, is there another tutorial for newbies aside from what you
get with FreeRide

 

[Robert Klemme]

i was trying the tutorials for ruby and they gave this code it seems to
have an error well anyway this is the code so whats wrong with it

class Song2
attr_reader :name, :artist, :duration
end
aSong = Song2.new("Bicylops", "Fleck", 260)
aSong.artist #» "Fleck"
aSong.name #» "Bicylops"
aSong.duration #» 260


can anyone tell me whats wrong here

this is what the error looks like
...4:in `initialize': wrong number of arguments (3 for 0)
(ArgumentError)
from F:/junji/ruby-study/class/song2.rb:4

Thanks all, is there another tutorial for newbies aside from what you
get with FreeRide

You'll have to define a method initialize with three parameters in order
to call new with three arguments.

In your case there's an easier solution:

Song2 = Struct.new :name, :artist, :duration
aSong = Song2.new("Bicylops", "Fleck", 260)

Kind regards

robert

 

[James Herdman]

You'll have to define a method initialize with three parameters in order
to call new with three arguments.

In your case there's an easier solution:

Song2 = Struct.new :name, :artist, :duration
aSong = Song2.new("Bicylops", "Fleck", 260)

Kind regards

robert

You're probably working through "Programming Ruby" at the moment.
These code snippets are meant to be typed into IRB one after the other.
Something you might want to do is write each snippet into a text file
instead of having to type out each snippet everytime.

Once you have these snippets in a text file, you can open them in IRB
by typing the following: load 'file_name.rb'.

Although there's nothing wrong with Robert's solution (which I'll talk
about in a second), it won't help you with all of the examples in the
book as most of them take the approach of building classes and methods
in a piecemeal manner.

Robert's solution uses Struct. Struct is to classes as attr_reader,
attr_writer, attr_accessor are to getters and setters.

When Robert said:
Song2 = Struct.new :name, :artist, :duration

This has the same effect as typing out:
class Song2
attr_accessor :name, :artist, :duration
end

I hope this helps,

James H.

 

[Robert Klemme]

You're probably working through "Programming Ruby" at the moment. These
code snippets are meant to be typed into IRB one after the other.
Something you might want to do is write each snippet into a text file
instead of having to type out each snippet everytime.

Once you have these snippets in a text file, you can open them in IRB by
typing the following: load 'file_name.rb'.

Although there's nothing wrong with Robert's solution (which I'll talk
about in a second), it won't help you with all of the examples in the
book as most of them take the approach of building classes and methods
in a piecemeal manner.

Yeah, that's likely true.

Robert's solution uses Struct. Struct is to classes as attr_reader,
attr_writer, attr_accessor are to getters and setters.

In other words: Struct.new creates a new class with defined properties.

When Robert said:
Song2 = Struct.new :name, :artist, :duration

This has the same effect as typing out:
class Song2
attr_accessor :name, :artist, :duration
end

No, Struct does far more. Defining the attribute accessors is just one
of them. You'll also get comparison, hash and a proper initialize
method - which is the reason I posted this suggestion.

Kind regards

robert

 

[junji]

Struct sounds like from C, thanks i'll try this later

 

[junji]

indeed I am working through "Programming Ruby" I was also thinking that
perhaps the codes are depricated, but anyhow I'll try robert's
solution, thanks all