RubyGems repository - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to install a gem named 'rails' using RubyGems.

Ruby

system('gem [1] rails')

Drag options to blanks, or click blank then click option'

Aupdate

Buninstall

Clist

Dinstall

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'update' instead of 'install' will try to update an existing gem.

Using 'uninstall' removes a gem instead of installing it.

The gem install command installs a gem from the RubyGems repository.

2fill in blank

medium

Complete the code to list all installed gems using RubyGems.

Ruby

system('gem [1]')

Drag options to blanks, or click blank then click option'

Alist

Bupdate

Csearch

Dinstall

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'install' tries to add a new gem instead of listing.

Using 'search' looks for gems online, not installed ones.

The gem list command shows all gems installed on your system.

3fill in blank

hard

Fix the error in the code to search for a gem named 'nokogiri' in the RubyGems repository.

Ruby

system('gem [1] nokogiri')

Drag options to blanks, or click blank then click option'

Ainstall

Bsearch

Clist

Duninstall

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'install' tries to add the gem instead of searching.

Using 'list' only shows installed gems, not available ones.

The gem search command looks for gems in the RubyGems repository.

4fill in blank

hard

Complete the code to create a hash that maps gem names to their versions for gems with version greater than 2.0.

Ruby

gems = gem_list.each_with_object({}) { |(name, version), h| h[name=>version] = version if version [1] '2.0' }

Drag options to blanks, or click blank then click option'

A=>

B>

C<

D:

Attempts:

3 left

💡 Hint

Common Mistakes

Using ':' instead of '=>' for hash mapping.

Using '<' instead of '>' for version comparison.

In Ruby, hashes use h[name => version] to map keys to values within each_with_object({}). The condition checks if version is greater than '2.0'.

5fill in blank

hard

Fill all three blanks to create a hash that maps gem names in uppercase to their versions if version is less than '3.0'.

Ruby

result = gems.each_with_object({}) { |(name, version), h| h[name[1] => version] if version [2] '3.0' and name[3] }

Drag options to blanks, or click blank then click option'

A.upcase

B<

C!= ''

D.downcase

Attempts:

3 left

💡 Hint

Common Mistakes

Using '.downcase' instead of '.upcase'.

Using '>=' instead of '<' for version comparison.

Not checking if name is not empty.

The .upcase method converts the gem name to uppercase. The condition checks if version is less than '3.0' and name is not empty.

Practice

1. What is the primary purpose of the RubyGems repository?

easy

A. To store and share Ruby libraries called gems

B. To compile Ruby code into machine language

C. To run Ruby programs faster

D. To create graphical user interfaces in Ruby

Solution

1. Step 1: Understand what RubyGems stores

   RubyGems repository is known for storing Ruby libraries called gems.

2. Step 2: Identify the main function

   Its main function is to share these gems so developers can reuse code easily.

3. Final Answer:

   To store and share Ruby libraries called gems -> Option A

4. Quick Check:

   RubyGems = Ruby libraries storage [OK]

Hint: RubyGems = place for Ruby code packages [OK]

Common Mistakes:

• Thinking RubyGems compiles code
• Confusing RubyGems with Ruby interpreter
• Assuming RubyGems runs programs

2. Which command correctly installs a gem named rails from the RubyGems repository?

easy

A. gem install rails

B. install gem rails

C. ruby gem add rails

D. gem add rails

Solution

1. Step 1: Recall the correct gem installation syntax

   The standard command to install a gem is gem install gem_name.

2. Step 2: Match the command with the gem name

   For the gem named rails, the command is gem install rails.

3. Final Answer:

   gem install rails -> Option A

4. Quick Check:

   Install gem = gem install [OK]

Hint: Use 'gem install gemname' to add gems [OK]

Common Mistakes:

• Swapping 'install' and 'gem' order
• Using 'gem add' instead of 'gem install'
• Adding extra words like 'ruby' before command

3. What will be the output of this Ruby code if the gem 'json' is installed?

require 'json'
puts JSON.generate({name: 'Ruby', type: 'language'})

medium

A. SyntaxError

B. {name: Ruby, type: language}

C. {"name":"Ruby","type":"language"}

D. nil

Solution

1. Step 1: Understand the require statement

   The code requires the 'json' gem, which provides JSON methods.

2. Step 2: Analyze JSON.generate output

   JSON.generate converts the Ruby hash to a JSON string with keys and values in quotes.

3. Final Answer:

   {"name":"Ruby","type":"language"} -> Option C

4. Quick Check:

   JSON.generate outputs JSON string [OK]

Hint: JSON.generate outputs string with quotes [OK]

Common Mistakes:

• Expecting Ruby hash syntax as output
• Confusing JSON.generate with JSON.parse
• Ignoring quotes around keys and values

4. Identify the error in this Ruby code snippet that tries to use the 'httparty' gem:

require 'httparty'
response = HTTParty.get('https://api.example.com/data')
puts response.body

medium

A. Missing parentheses in the require statement

B. The method 'get' does not exist in HTTParty

C. Cannot call 'body' on response

D. The gem 'httparty' is not installed

Solution

1. Step 1: Check if 'httparty' gem is installed

   If the gem is not installed, require will fail or HTTParty will be undefined.

2. Step 2: Verify method and usage

   HTTParty.get is a valid method, and response.body is valid if response is returned.

3. Final Answer:

   The gem 'httparty' is not installed -> Option D

4. Quick Check:

   Missing gem causes require failure [OK]

Hint: Install gem before requiring it [OK]

Common Mistakes:

• Assuming require adds gem automatically
• Thinking 'get' method is invalid
• Ignoring gem installation step

5. You want to create a Ruby script that uses the 'colorize' gem to print text in red. Which sequence of steps is correct?

hard

A. Run require 'colorize', then gem install colorize, then use puts 'text'.colorize(:red)

B. Run gem install colorize, then require 'colorize', then use puts 'text'.colorize(:red)

C. Use puts 'text'.colorize(:red) directly without installing or requiring

D. Run gem add colorize, then require 'colorize', then use puts 'text'.colorize(:red)

Solution

1. Step 1: Install the gem first

   You must install the gem using gem install colorize before using it.

2. Step 2: Require the gem in your script

   Use require 'colorize' to load the gem's code.

3. Step 3: Use the gem's method to color text

   Call puts 'text'.colorize(:red) to print red text.

4. Final Answer:

   Run gem install, then require, then use colorize method -> Option B

5. Quick Check:

   Install -> require -> use gem [OK]

Hint: Install gem before require and usage [OK]

Common Mistakes:

• Requiring gem before installing
• Using 'gem add' instead of 'gem install'
• Trying to use gem methods without require