Task Discussion

Roelof said:

Here my answers :

https://github.com/roelof1967/homework/tree/master/reflecting%20exercise%201

Again I hope someone will look if the answers are allright

Roelof

on Aug. 29, 2013, 12:30 p.m.
Andre Dublin said:
For the second question

If you open up irb (ruby interpreter) in your console and input what you provided you will be given an error

irb(main):001:0> 1.000.000.000 SyntaxError: (irb):1: no . floating literal anymore; put 0 before dot 1.000.000.000 ^ (irb):1: syntax error, unexpected tINTEGER 1.000.000.000 ^ (irb):1: no . floating literal anymore; put 0 before dot 1.000.000.000 ^ from /usr/local/var/rbenv/versions/1.9.3-p392/bin/irb:12:in `'

The correct syntax is

irb(main):002:0> 1_000_000_000 => 1000000000

For the extra credit question:

The reason that you can apply the "+" operator to number and strings is because of Ruby's object inheritance. You will come to find out that Ruby objects all inherit from Object and there are methods hidden up the chain that allow them to be applied to different types of objects. If you open your ruby interpreter and type in the following, it will give you a basic understanding of how Ruby finds its methods

1.class.superclass.class.superclass.superclass

This is the road down metaprogramming in ruby.
on Aug. 29, 2013, 1:10 p.m. in reply to Roelof
Roelof said:

Thanks for the feedback. Can I continue or can I better read more about this subject.

on Aug. 29, 2013, 1:16 p.m. in reply to Andre Dublin

Andre Dublin said:

Yes you can contiune. And I highly recommend reading more about metaprogramming in ruby.

on Aug. 29, 2013, 1:17 p.m. in reply to Roelof

Roelof said:

Thanks Can you recommend a good tutorial about that.

on Aug. 30, 2013, 10:13 a.m. in reply to Andre Dublin

Andre Dublin said:

Nothing can beat this book when it comes to learning about this topic

http://www.amazon.com/Metaprogramming-Ruby-Program-Like-Pros/dp/1934356476

As for tutorials online, Im sure you can do a search online and find a lot of sources out there.

But one that I recommend are from the rubylearning.com guys

http://ruby-metaprogramming.rubylearning.com/

on Aug. 30, 2013, 10:24 a.m. in reply to Roelof
Si Dunn said:

I've posted mine here...

https://github.com/sidunn/coursework/blob/master/thinking_caps1.rb

on Nov. 28, 2012, 4:31 p.m.
Jure said:

I've done it here:

https://raw.github.com/Hoornet/coursework/master/thinking_hat_1.rb

on Oct. 29, 2012, 10:14 a.m.
David O'Dowd said:

https://github.com/davidodowd/coursework/blob/master/ltp/reflections.rb

on Oct. 11, 2012, 11:51 p.m.

Andre Dublin said:

Looking good David, sorry for the late response.

on Oct. 19, 2012, 4:09 p.m. in reply to David O'Dowd
Ajiwo said:

https://github.com/ajiwo/coursework/blob/master/reflection.rb

on Aug. 30, 2012, 9:16 a.m.
sedmonds said:

Submitted: https://github.com/sedmonds/p2pu_ltp/blob/master/Week-1/reflections.rb

on March 29, 2012, 2:03 p.m.
Peter Hwang said:

I don't remember reading about prints. Can someone point me where we were supposed to learn that? Same goes for placing a variable inside a string. Not sure how I missed those two concepts.

on March 22, 2012, 12:59 a.m.

Anonym said:

Hi Peter,

You are right about the string. LTP doesnt mention this in first chapters. I have picked up up the placing variable inside a string method from other resources (ruby-doc, first chapter about printing strings). I also use 'Beginning Ruby' from Apress.

on March 22, 2012, 2:16 a.m. in reply to Peter Hwang

Andre Dublin said:

Yes, questions will take a little research.

on March 22, 2012, 9:01 a.m. in reply to Anonym
Haitham Gasim said:

Hi ...

Where should we put the answers to the discussion questions?

Thanks.

Haitham

on March 19, 2012, 11:32 p.m.

Haitham Gasim said:

Great.

Here you go.

1) What is the difference between puts and print?

puts adds a newline character if it's not present at the end of the string while print doesn't.

2) For big numbers (thousands, millions, billions etc) what is an alternative syntax that ruby provides? Provide an example.

underscores can replace comma separators without any rules. Eg: 25000000 can be written as 25_000_000 which is the equivalent of 25,000,000

3) What do these methods do? to_s, to_i, puts, gets, chomp

to_s: produces the string verion of an object

to_i: produces the integer version of an object

puts: (put string) writes out an object by applying to_s to it to get its string version

gets: reads a string from the input until return is hit

chomp: removes trailing edge new line characters from input strings

4) What is the programming term when you place a variable inside a string like so: "Author is #{author_age_in_years} years old."

Embedded Evaluation: will evaluate only strings enclosed with double quotes

Extra Credit: Explain why in Ruby you can use the "+" operator to add numbers and build strings?

"+" in Ruby will output the concatenation of muliple strings and the sum of multiple numbers:

puts 'dog ' + 'cat' will output dog cat

puts 1 + 1 will output

on March 20, 2012, 8:17 a.m. in reply to Andre Dublin