You want to process a large file line by line without loading it all into memory. Which lazy enumerator method chain is best?

hard📝 Application Q8 of 15

Ruby - Functional Patterns in Ruby

AFile.open('file.txt').lazy.select { |line| line.include?('error') }

BFile.readlines('file.txt').lazy.select { |line| line.include?('error') }

CFile.read('file.txt').lazy.select { |line| line.include?('error') }

DFile.foreach('file.txt').lazy.select { |line| line.include?('error') }

Step-by-Step Solution

Solution:

Step 1: Identify memory-efficient file reading
File.foreach reads file line by line lazily, ideal for large files.
Step 2: Analyze other options
File.readlines reads entire file into memory; File.read reads whole file as string; File.open returns file object but needs iteration.
Final Answer:
File.foreach('file.txt').lazy.select { |line| line.include?('error') } -> Option D
Quick Check:
Lazy file processing = File.foreach + lazy + select [OK]

Quick Trick: Use File.foreach with lazy for memory efficiency [OK]

Common Mistakes:

Master "Functional Patterns in Ruby" in Ruby

9 interactive learning modes - each teaches the same concept differently

Want More Practice?

15+ quiz questions · All difficulty levels · Free

More Ruby Quizzes