Learnings along the way of completing the Roman Numerals Kata via Exercism

• Roman Numerals Kata
  • Things that I applied or learnt along the journey that led to the final solution -
  • Approach the problem in small steps. I was solving this kata for the first time, I didn't know of any pattern whatsoever initially, hence took this problem, one step at a time and it eventually helped me get to solution. Often times one worries about the end solution or just the destination, without traveling the journey bit by bit.
    • I know you may think this approach(solving for one test at a time as done in this commit and this one) wouldn't give you the desired solution that'll satisfy all cases, but trust me it will help you eventually get there. That's why this approach is worth it.
  • Used the older hash syntax in ruby so that I could leverage keys as strings. With this I could do away with the to_s that I was using here.
  • Learnt that I don’t have to use a more higher order class like the Numeric class. Instead, I could use Fixnum. I also learnt about the hierarchy of these classes. Numeric is the parent of Integer which in turn is the parent of Fixnum.
  • Learnt that reverse_each is much faster than using reverse.each and made the relevant refactoring here
  • Refactoring related learnings * When I was looking at other people's solution like that of rwz's, I realized I can define my ROMAN_NUMERALS related hash in the reverse order like what was done here and thereby I wouldn't even need to use the reverse_each method, saving me an additional computation. * I learnt that I could further simplify my solution after referring to rwz's solution. The if...else related branches that I had introduced to handle the subtractive notation related to roman numerals can be dealt without using that amount of branching. I made the relevant changes wrt this learning in this commit. * Learnt how we could use each_with_object to do away with a temp variable from henrik's solution. Appropriate change was made in this commit. Below is how the code looks before and after using each_with_object

Before

  def to_roman
    num = ''
    number_to_convert = self

    ROMAN_NUMERALS.each do |roman_numeral, numeric_equivalent|
      next if numeric_equivalent > number_to_convert

      quotient, remainder = number_to_convert.divmod(numeric_equivalent)
      number_to_convert = remainder
      num << roman_numeral * quotient
    end

    num
  end

After

  def to_roman
    number_to_convert = self

    ROMAN_NUMERALS.each_with_object("") do |(roman_numeral, numeric_equivalent), roman_equivalent|
      next if numeric_equivalent > number_to_convert

      quotient, remainder = number_to_convert.divmod(numeric_equivalent)
      number_to_convert = remainder
      roman_equivalent << roman_numeral * quotient
    end
  end
  

• I'd like to leave you with one last thought wrt solving this kata. Jim Weirich when solving this kata at RubyConfIndia 2013 said(start listening from 7:52 onwards),

I don't want to write code for special cases until I understand the general case first.

 For me, this was something I wasn't doing very consciously all this while but I felt, it's definitely something              worth reflecting upon and further experimenting with.

• Wrapping up, I would like to thank Jim for the above thought and for his work that has helped so many people. Also, my learnings here wouldn't have been possible without those who've contributed to exercism and to those whose solution I had an opportunity to refer to. I'm thankful to them as well.

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Learnings from solving the Hamming exercise on Exercism

Hamming Exercise

• Learnt how to use count with each_with_index
  • This helped me do away with the temp variable distance that I had used as a counter.

Before - Uses a temp variable called distance as a counter

class Hamming
  VERSION = 1

  def self.compute(dna_strand_1, dna_strand_2)
    raise ArgumentError if dna_strand_1.length != dna_strand_2.length
    distance = 0
    dna_strand_1.chars.each_with_index do |strand_1_char, index|
      distance += 1 unless strand_1_char == dna_strand_2[index]
    end
    distance
  end
end

After - Uses count insead of distance . Taken from rwz's solution.

class Hamming
  VERSION = 1

  def self.compute(dna_strand_1, dna_strand_2)
    raise ArgumentError if dna_strand_1.length != dna_strand_2.length

    dna_strand_1.chars.each_with_index.count do |strand_1_char, index|
       strand_1_char != dna_strand_2[index]
    end
  end
end

• Looking back at this new approach I could relate better to the Nitpick made in my solution by rikki - the friendly neighborhood code review robot, who said -

Whenever you are looping through a collection and find yourself writing a conditional (if or unless) nested inside of the loop, take a moment to look through the available enumerable methods. There are some very handy ones that might let you simplify.

Misc Learnings

• Use chars to get an array of characters from a string
• Use zip to merge corresponding elements of two or more arrays as used wrt henrik's solution. Sample usage -

2.3.0 :008 > b = [7, 9]
2.3.0 :009 > c = [4, 8]
2.3.0 :010 > a = [2, 3]
 => [2, 3]
2.3.0 :011 > a.zip(b)
 => [[2, 7], [3, 9]]
2.3.0 :012 > a.zip(b,c)
 => [[2, 7, 4], [3, 9, 8]]
2.3.0 :013 >

• Learnt that one needn't have to use a class always(using a class was the first thing that came to my mind when solving this). A module could also be used to solve this. The reasoning behind this(mentioned below) is something I hadn't thought of earlier. It also kinda makes sense to me becuase with Modules one cannot create instances of it and if there isn't a need to create instances, then why not consider using a module. People may want to debate further on this(i.e., on using classes vs modules - that's beyond the scope of this post) but the below point in itself was something worth reflecting upon for me.

  • In tejasbubane's solution Katrina Owen said..

  Yeah, there's not much reason to use a class for this, since there are no instances involved over here.

• Something similar was also mentioned in markijbema's solution.

Lastly, my learnings here wouldn't have been possible without those who've contributed to exercism and to those whose solution I had an opportunity to refer to. I'm thankful to them.

view raw hamming_learnings.md hosted with ❤ by GitHub

Learnings from using Hound and friends

A few months back I built a basic expenses web app from scratch using Rails, SCSS, Bootstrap and friends. Working single handedly on a project has it's own pros and cons. When I started work on this project, one thing that I really wished for was to get constant feedback on the code that I wrote as that would help me write better code. As a programmer, by yourself, one can identify a number of things that may be wrong with your code but sometimes that ‘AHA’ moment may only come from somebody else’s feedback on your code.

via GIPHY

When I was working on this app, I didn’t explicitly have somebody out there to give me feedback but I was luckily in the company of tools like Hound to help me with some feedback. Hound is a tool that comments on style violations with respect to your Github pull requests, allowing oneself and their team to better review and maintain a clean codebase. This post basically highlights some of the ways through which Hound and it’s friends(rubocop etc., that hound uses internally) helped me learn new things that eventually helped me write better code .

My Learnings -

1. “Do not use Date.today without zone. Use Time.zone.today instead.” - as mentioned in this comment

Learnings -

1. From this SO answer - Time.zone.now will use the applications time zone, while Date.today will use the servers time zone. So if the two lie on different dates then they will be different.
2. And as mentioned in this post -

You might notice that DateTime.now and Time.now both give you the time in system time zone. And it definitely makes sense since these are Ruby standard library methods that know nothing about Rails time zone configuration. Time.zone.now on the contrary is provided by Rails and respects Time.zone value that we set in Rails.

2. “Color white should be written in hexadecimal form as #ffffff

Color literals like white should only be used in variable declarations; they should be referred to via variable everywhere else.” - as mentioned in this comment

Learnings -  

I learnt that one should more consciously make use of the variables feature provided by SCSS. Using variables promotes reusability.

3. "Extra empty line detected at block body end" - as mentioned in this comment.  

Learnings -

This helped me to remove extra empty lines from my code. There are times when you submit a PR and you may forget about removing such things and for any person who is new to your code might find it confusing to see the presence of extra empty lines in some parts of your code and their absence in other parts.

4. "Redundant curly braces around a hash parameter. Space inside { missing. Space inside } missing" - as mentioned in this comment .

Learnings -

This comment talks about removing unnecessary code in the context of better code readability. Also, adding additional spaces where appropriate is any day more soothing to the eye.

5. "Files should end with a trailing newline" - as mentioned in this comment

Learnings -

According to POSIX, every text file (including Ruby and JavaScript source files) should end with a \n, or “newline” (not “a new line”) character as mentioned in this thoughtbot blog.

One can read more about how this is useful by following this Stackoverflow thread as well.

6. "Keep a blank line before and after private" - as mentioned in this comment

Learnings -

This basically helps separating one thing from another. This way, one can explicitly showcase how a particular line of code is in a way different from another.

7. "Prefer double-quoted strings unless you need single quotes to avoid extra backslashes for escaping." - as mentioned in this comment

Learnings -

When I think about this comment. What basically comes to my mind is that I need to ensure there is consistency in different parts of my codebase whenever I consider using quotes. I would like to leave this at it as many people have more stronger opinions on the usage of quotes and I believe that's beyond the scope of what this post was intended for in the first place.

Takeaways

I made appropriate changes to my code based on whatever hound related suggestions were understandable to me at that given point in time. For all of those programmers out there, especially those who are code newbies, tools like these can offer you really good guidance for starters . Even if you’re a programmer with some experience, you may learn something new on the design and/or development side when you try using hound and this definitely ends up giving a person more confidence to write better code.

I’m thankful to Thoughtbot, all those who’ve contributed to Hound and also to those people who have contributed to tools/libraries similar to rubocop that have helped hound to give constant feedback on our pull requests. I’m also thankful to Michael Hartl for his Rails tutorial as that was the reference that I used when going about building the expenses app.

How to get Elixir syntax highlighting in github markdown files

Very recently I've started to try out the elixir programming language. As I go about exploring the language through different experiments, I was thinking of making notes of learnings along the way in markdown files. I knew how ruby syntax highlighting works(please see the screenshot below) but didn't know the exact way to do this in elixir.




I've subscribed to a beginners channel in the elixir-lang slack group(you can get your invite here) . Karmen Blake(kblake on the slack group) and Andrea Rossi(lucidstack on the slack group) from that group were quick to help me out with the right syntax for highlighting elixir code in a markdown file. Here's how you can get elixir syntax highlighting in your markdown file -




Here's a github gist of how it looks. You can look at the raw gist to see the exact syntax that you may need to use. Below is a screenshot of how the highlighted syntax looks in a markdown file.



I would like to thank Karmen Blake and Andrea Rossi for helping out from the elixir community :). I think you should definitely hangout in the beginners channel of their slack group if you're just getting started with elixir.

Cheers.

P.S: It's been a while since I've written my last post. I had been held up with a few things in the past but I hope to write more often going forward. Thanks for your patience.