Newb: an explaination for this if statement

Ruby
1

Hi. I’m confused as to why this variable* is nessesary:

def add_product(product)

existing_product = @items.find {|item| item.product == product}

if existing_product
existing_product.increment_quantity

    else
    existing_product = CartItem.new(product)
    @items << existing_product

end

existing_product*

end

i’m a newb, and to a newb, i can’t understand why a var just sits there.
can someone please explain what the purpose of exisiting_product* is?

i’d figure exisiting_product* wouldn’t be needed since on the 2nd line,
existing_product is initialized with @items.find…blahblahblah…

2

Hi –

On Thu, 13 Jul 2006, Dominic S. wrote:

i’m a newb, and to a newb, i can’t understand why a var just sits there.
can someone please explain what the purpose of exisiting_product* is?

i’d figure exisiting_product* wouldn’t be needed since on the 2nd line,
existing_product is initialized with @items.find…blahblahblah…

The last line is equivalent to:

return existing_product

If there’s no explicit “return” statement, then the method returns the
value of the last expression evaluated – which, in this case, is:

existing_product

David

3

Dominic S. wrote:

i’m a newb, and to a newb, i can’t understand why a var just sits there.
can someone please explain what the purpose of exisiting_product* is?

i’d figure exisiting_product* wouldn’t be needed since on the 2nd line,
existing_product is initialized with @items.find…blahblahblah…

In Ruby, methods return the value of the last expression if there is no
explicit return. That’s why it looks like existing_product is just
sitting there. It’s the same as:

def add_product(product)

...stuff..

return existing_product

end

-Justin

4

Hey Mr David. I really appriciate you helping me.

Thank you : )

Dominic

unknown wrote:

Hi –

On Thu, 13 Jul 2006, Dominic S. wrote:

i’m a newb, and to a newb, i can’t understand why a var just sits there.
can someone please explain what the purpose of exisiting_product* is?

i’d figure exisiting_product* wouldn’t be needed since on the 2nd line,
existing_product is initialized with @items.find…blahblahblah…

The last line is equivalent to:

return existing_product

If there’s no explicit “return” statement, then the method returns the
value of the last expression evaluated – which, in this case, is:

existing_product

David

5

Dominic S. wrote:

Hi. I’m confused as to why this variable* is nessesary:

def add_product(product)

[snip]

existing_product*

end

In Ruby, the last expression executed becomes the return value of the
method.

The code could have said:

return existing_product

but the “return” keyword is actually optional in this case.

Jeff

6

[email protected] wrote:

existing_product = @items.find {|item| item.product == product}
existing_product*

David

Well, I don’t know how other feels, but I’d put it in another way: In
Ruby the value of a sequence of expressions is the last expression. Now,
the return value of a function is the value of its content … thus the
value of its last expression. “return” is, in ruby, only useful if you
want to return from the function before the end of the body of the
function (like break in an iterator will interrupt the iteration
returning the value after the break).

Pierre

7

Jeff C. wrote:

Jeff
softiesonrails.com

So why not just use “return existing_product”
it definetily states its intent
also implies that the return value should be caught.

lots of methods can return values that do not need to be caught such as
puts which always returns nil

8

I would’ve thanked you too Justin! we posted literally at the same time!