solving error messages - learning ruby the hard way

Learning Ruby The Hard Way | How I Beat the Un-stoppable Error Messages

Posted on Posted in Ruby, Software Engineering

Trouble shooting exercise 25 of learning ruby the hard way by zed

I have enrolled at the intense computer programming bootcamp, the Maker Academy, next month. To get a head start I thought I would work through Zed Shaw’s Learn Ruby the Hard Way book.

Exercise 25 seems to be testing my problem solving skills so I thought I would write a post documenting how I worked out then fixed my error messages. This post is aimed at newbies to the programming world as I imagine it is very basic things which I am getting wrong.

First Script – The Start of the Problem 

This was my first attempt at writing exercise 25’s script in my editor:

exercise 25 of Learn ruby the hard way by zed shaw error messages

 

 

 

 

 

 

 

 

 

 

 

 

When I ran this in the terminal I got the following error message:

ex25.rb:2:in `<main>’: undefined local variable or method `ex25′ for main:Object (NameError)

The first thing I did was google the error message.

Solving the Error Message with Google 

I found an answer on Stackoverflow. It told me I was accidentally typing Alt + Space on my Mac, therefore creating non-breaking space. That this is considered by Ruby as part of the variable name as opposed to the whitespace it was intended to be.

It gave two solutions to this problem:

1.  Remapping Alt + Space to space to stop this typo occurring again.

2. Highlighting invisible characters in text editor to immediately realise the typos.

 

The preference seemed to be for solution 2  so I thought I would try this way first. It seemed the most simple and quick to fix. I wanted to rule out the off-the-shelf issue to my broken code.

Highlight invisible characters in my text editor – Part 1

Next I googled how to highlight invisible characters with my text editor, Sublime Text editor 2.

Turns out this is supposed to be a default feature of my text editor. Every time I highlight text I am supposed to be able to see little white dots like the image below (look close they are there in the empty spaces):

how to highlight invisible characters with Sublime Text editor 2

 

 

 

 

 

 

 

 

So I highlighted the text and nothing happened:

textselected in sublime text editor 2 learn ruby the hard way ex25

 

I decided to park the problem of ‘non-breaking’ spaces here for now and try and solve my error message an easier way. I am relatively new to coding so the next solution for finding ‘non-breaking’ spaces, fixing the preferences or default key assignments in Sublime Text editor, did not seem like the easiest way to solve my problem.

Googling the exercise itself

The next thing I did was google ‘Ex25 learn Ruby the hard way’ to see if anyone else was having the same issues as I was. I found a blog with the exercise typed out. I compared our files word for word on my screen.

I could not SEE any difference between our files (indicating the hidden non-breaking spaces may be what is causing my error).

However I needed to rule out the idea there was a typo I couldn’t spot somewhere, so I typed out the whole file again. Figuring this was a quicker way to get to the solution.

My second file worked when I ran it in the terminal. No error message.

Here is the second file:

Script for exercise 25 learn ruby the hard way. no errors

I was intrigued where I went wrong with the first file still, so I compared them line for line.

Comparing the working script to the one with an error message

Compared them on my screen and noticed two differences which I fixed one at a time.

exercise 25 of learn ruby hard way. Errors

1.  When the earlier functions were called in later ones eg.

def ex25.print_first_and_last(sentence)

words = ex25.break_word ..

The ex25.break_word function looked like it had not been recognised in the error script (one on the right) whereas the Ex25. appeared blue in the other script (left).

The most obvious reason I could come up with  was that the ‘e’ wasn’t capitalised. So I changed all Ex25’s in the broken script to a capitalised e.

exercise 25 of learning ruby the hard way, broken script

 

I ran the script but still got the same error message:

ex25.rb:2:in `<main>’: undefined local variable or method `ex25' for main:Object (NameError)
2. The next easy fix I noticed was the file name and the function name in the broken script were the same but in my new script I had named the file EX25b.rb.

Maybe it was this difference in naming which was responsible for the error?

Nope ..

ex25.rb:2:in `<main>’: undefined local variable or method `ex25' for main:Object (NameError)

Had I read the whole of the exercise in Learning Ruby the Hard Way I would have seen this wasn’t the answer:

“The Ex25 module doesn’t have to be in a file named ex25.rb. Try putting it in a new file with a random name then import that file and see how you still have Ex25 available.”

So I decided to go back to the first solution, non-breaking space as I had now exhausted the easy options and couldn’t for the life of me  see any difference between the error or the correct script.

Highlight invisible characters in my text editor- Part 2 

I read how to do this here.

1.  Open the ‘preferences’ within Sublime text editor & select ‘key bindings’.

Preferences, key bindings within Sublime text editor 2

 

 

 

 

 

 

2.   Insert into the left side, the ‘user’ tab the following code:

{

"keys": ["alt+space"],
"command": "insert_snippet",
"args": {"contents": " "}

}


User tab of key binding sublime text editor

code inserted sublime text editor changing key bindings to show up alt + space bar on macs

 

 

 

 

 

 

 

 

 

 

 

 

 

 

3.   Saved then re-opened the original (broken 🙁 ) file.

Sure enough there was the accidental Alt and space bar non-breaking space:

Alt and Space bar error on a mac and sublime editor 2

 

 

HALLELUJAH .. I thought.. I have finally fixed my old script…….

I ran it again and I STILL had the same error message!

Here is where I probably should have thought:

“I got it correct once and managed to work through the exercise and complete it. I will just call it a day and not worry about the file which is returning an error message”.

But I am too curious / stubborn to settle for just allowing the error to hang over my first script.

I ran irb in the terminal.

I ran the file I had got correct again & the file with the error message:

Error message in terminal. Incorrect Ex25 of learning Ruby the hard way

I tried to work out what was the difference between the two files.

Maybe it was the directories they were saved in?

I check and sure enough they were saved in different directories.

So I saved the error file in the same directory as the file that worked…. STILL the error message!!

I could see no other difference so I ….

Copied and pasted the text from the working file to the error file.

Then something terrible happened!

BOTH the files stopped working!!!!

The same error message appeared for the first file and now the working file was returning ‘false’ when I ‘required’ it with irb:

Ex25 script from learn ruby the hard way returning false in the terminal

Possible cause of this problem:

Too many files with the same or similar name in the same directory?

I deleted all but one… And like magic ..

IT WORKED !!!

I ran the working script for Ex25 in the terminal and followed the instructions on how to use irb to call it’s functions.

Here are my results and my explanation of what is happening:

The correct script for Ex25

Script for exercise 25 learn ruby the hard way. no errors

Running the script in command line ‘irb’

Ex25 in the terminal correct

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

I have labeled the points where I had to think a bit about how it was working. Here is my explanation:

1.   Prints ‘wait’  because the function is acting on the ‘words’ array which is not sorted. The sorted array is called ‘sorted_words’.

2.   ‘Words’ array has had the first and last (“all’ and ‘wait’ ) values shifted off  in the print function.

3.  Calling on the ‘sorted_words’ array, not the ‘words’ array which has the missing values. Therefore ‘all’ is still in the array.

4….Seems to be missing from the picture … So I clearly deemed it irrelevant then therefore i will do the same again now..

5.  Using the original ‘sentence’ variable and passing this through the function. It is breaking this sentence variable into an array every time it encounters a space. Then using Ex25.sort_words function to sort this array of words.

6.  It is taking the original variable ‘sentence’, breaking it into an array of words then printing the first and last value of that array.

 

So we have now come to the end of my struggling with exercise 25 of Learn Ruby the Hard way. I hope you have enjoyed and found useful  my higgledy piggldy problem solving which eventually resulted in me beating the error messages given by running my script.  Please do contact me if you are by a slim chance reading this & need any help understanding it.

Enjoy, 🙂

6 thoughts on “Learning Ruby The Hard Way | How I Beat the Un-stoppable Error Messages

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