Forum: Ruby fasterCSV meaning of a line

What is the meaning of line?:

if !in_quotes || in_quotes[@parsers[:stray_quote]]

at line approx 1643 in faster_csv.rb

!in_quotes   => if in_quotes is nil or false

in_quotes[....]   => calls the #[] method on in_quotes with the given 
argument

So this is effectively saying:

    if in_quotes[@parsers[:stray_quote]]

but with a get-out clause which avoids the line bombing out if in_quotes 
is nil.

> in_quotes[....]   => calls the #[] method on in_quotes with the given
> argument

Is this functional programming?

If so or even if I am wrong, kindly help me with some pointer to 
understand it betetr and have better grip on RUBY!

> in_quotes[....]   => calls the #[] method on in_quotes with the given

What is #[] method?

Hi,

ajay paswan wrote in post #1071826:
>> in_quotes[....]   => calls the #[] method on in_quotes with the given
>> argument
>
> Is this functional programming?

What do you mean by "functional programming"?

As to the usual meaning of the word: no.



ajay paswan wrote in post #1071904:
>> in_quotes[....]   => calls the #[] method on in_quotes with the given
>
> What is #[] method?

It is the method that you define by

def [](...)
  ...
end

and call by

your_object[...]

It's the "indexing method" known from arrays:

arr = [1, 2, 3]
puts arr[0]  # <-- this calls the "[]" method of the Array class

Jan E. wrote in post #1071905:
> arr = [1, 2, 3]
> puts arr[0]  # <-- this calls the "[]" method of the Array class

Exactly.

In this case, because ruby is a dynamic language, what precisely it does 
depends on what objects @parsers and in_quotes represent at runtime. So 
you need to work back through the code to find where they are set.

At a guess, I would say @parsers is quite likely to be a Hash. If that's 
true, @parsers[:stray_quote] will get you the Hash value whose key is 
the symbol :stray_quote.

>> parsers = {:fluffy=>123, :wombat=>456}
=> {:fluffy=>123, :wombat=>456}
>> parsers[:fluffy]
=> 123
>> parsers[:wombat]
=> 456

But this isn't necessarily so; @parsers could be any object which 
implements a [] method.

>> saytwice = lambda { |x| x + x }
=> #<Proc:0x0000000101c2b6c0@(irb):9>
>> saytwice["hello"]
=> "hellohello"