Comparison between C++ and Ruby Variables

Ruby
1

I have blogged about the comparison between c++ and ruby variables and
it would great if people can comment on it if something should be
changed or I am missing some concept. Accordingly I can update the blog
as I want it to be correct, so that people are not misled by some wrong
information.

Thanks,
Mayank K.

2

On Wed, Mar 9, 2011 at 1:12 PM, Mayank K. [email protected]
wrote:

I have blogged about the comparison between c++ and ruby variables and
it would great if people can comment on it if something should be
changed or I am missing some concept.

A link to your blog post would help with that, I bet. :wink:

–
Phillip G.

Though the folk I have met,
(Ah, how soon!) they forget
When I’ve moved on to some other place,
There may be one or two,
When I’ve played and passed through,
Who’ll remember my song or my face.

3

On Wed, Mar 9, 2011 at 6:25 PM, Phillip G. <
[email protected]> wrote:

Phillip G.

Though the folk I have met,
(Ah, how soon!) they forget
When I’ve moved on to some other place,
There may be one or two,
When I’ve played and passed through,
Who’ll remember my song or my face.

Sorry guys totally missed it .Herr it is:
http://mayankkohaley.blogspot.com/

4

On Wednesday, March 9, 2011 3:05:13 PM UTC+1, Mayank K. wrote:

Sorry guys totally missed it .Herr it is: http://mayankkohaley.blogspot.com/

You write “The Class variable in Ruby is similar to static member
variable of C++.” This is not true. You also do not mention the
particular peculiarities that pop up when mixing class variables with
inheritance and initialization order. For a rough equivalent for static
members in C++ I would rather choose class instance variables.

Personally I would either not mention class variables, mention them and
say “don’t use them” or mention them, explain them and say “don’t use
them”.

Oh, and then there are nice things as static variables in methods in C++
as well… :slight_smile:

Kind regards

robert

5

On Wed, Mar 9, 2011 at 7:25 AM, Robert K.
[email protected] wrote:

On Wednesday, March 9, 2011 3:05:13 PM UTC+1, Mayank K. wrote:

Sorry guys totally missed it .Herr it is: http://mayankkohaley.blogspot.com/

You write “The Class variable in Ruby is similar to static member variable of
C++.” This is not true. You also do not mention the particular peculiarities that
pop up when mixing class variables with inheritance and initialization order. For
a rough equivalent for static members in C++ I would rather choose class instance
variables.

Personally I would either not mention class variables, mention them and say
“don’t use them” or mention them, explain them and say “don’t use them”.

Yeah. I’d concur. Explain them, but go into details as to why they are
generally not a good idea, and why class instance variables are
generally a much better choice.

I’d also explain that class instance variables are really just
instance variables. They aren’t a special case.

Kirk H.
Software Engineer
EngineYard

6

On Wed, Mar 9, 2011 at 3:56 PM, Mayank K.
[email protected] wrote:

You write “The Class variable in Ruby is similar to static member variable
of C++.” This is not true.

Can you please explain how exactly it is different from static member
variables of C++.

I am sorry, there is a ton of material on class variables and their
oddities online (even in the archives of this forum). Please look it
up.

Basically you cannot do that with static member variables in C++:

16:23:10 Temp$ ruby19 cv.rb
B1
2
S1
2
B2
1
S2
1
16:23:13 Temp$ cat -n cv.rb
1 class B1
2 @@foo = 1
3 def self.show; p @@foo; end
4 end
5 class S1 < B1
6 @@foo = 2
7 def self.show; p @@foo; end
8 end
9 class B2
10 end
11 class S2 < B2
12 @@foo = 2
13 def self.show; p @@foo; end
14 end
15 class B2
16 @@foo = 1
17 def self.show; p @@foo; end
18 end
19 [B1,S1,B2,S2].each do |cl|
20 puts cl
21 cl.show
22 end
16:23:16 Temp$

Kind regards

robert

7

On Wed, Mar 9, 2011 at 8:57 PM, Kirk H. [email protected] wrote:

would rather choose class instance variables.

Kirk H.
Software Engineer
EngineYard

Thanks a lot guys for inputs I have changed the blog post accordingly
with a
word of caution about the class variables.