Doubt with symbols in Rails

Rails
1

I was trying to write a wrapper for number_to_currency to return
currency in pounds. I used a helper class to do this.

def number_to_pounds(amt)
number_to_currency(amt, :unit => “”)
end

This works fine, but I am trying to understand why I can’t use a
symbol to pass the values. I thought symbols were like pointers. (you
now know I am a newbie).

def number_to_pounds(:amt)
number_to_currency(:amt, :unit => “”)
end

Note - amt is not the name of the variable my view works on, it is
price, so I tried the symbol :price, it wouldn’t work either. I am
googling to learn about the symbols. Any link for that would be really
helpful.

Thanks

2

On 16 Oct, 23:01, Arun S. [email protected] wrote:

A symbol is an interned string - :foo is a literal much like ‘foo’, []
or 3: it clearly does not make sense to declare a function with the
first argument being any sort of literal
http://blog.hasmanythrough.com/2008/4/19/symbols-are-not-pretty-strings
has some good stuff about symbols

Fred

3

thanks… I did read a lot about the difference between symbols and
strings. I have another question here regarding the internal workings
of rails and how it uses symbols.
I am following the pragmatic programmers book on rails developing the
depot application. Here I declare a scaffold line_item with two
integers to hold the relationship between the product and the cart.
In the cart controller- I use the symbol ‘:line_items’, no where did I
declare or even tell the universe there would be some symbol to denote
a line_item. Is this how rails works? a default symbol for models that
could be used to store the objects for that model to be used in
controllers?? If someone could link me to a blog post explaining this
rails character, I’ll be really happy.

Thanks
Arun

On Oct 16, 6:22pm, Frederick C. [email protected]

4

On Oct 17, 4:11pm, Arun S. [email protected] wrote:

I am following the pragmatic programmers book on rails developing the
depot application. Here I declare a scaffold line_item with two
integers to hold the relationship between the product and the cart.
In the cart controller- I use the symbol ‘:line_items’, no where did I
declare or even tell the universe there would be some symbol to denote
a line_item. Is this how rails works? a default symbol for models that
could be used to store the objects for that model to be used in
controllers?? If someone could link me to a blog post explaining this
rails character, I’ll be really happy.

This isn’t really about rails. :line_items is just a literal - you
don’t have to declare it, just as you don’t have to declare the string
“line_items”: typing it is enough to bring it into existance. You
might also want to read
http://glu.ttono.us/articles/2005/08/19/understanding-ruby-symbols

Fred