Quine about quines

quine_about_quines.rb

# Quines are programs that print their own source code
# This program is a quine that explains how some Ruby quines work

# This first one uses a heredoc with 2 as the delimiter
# The beginning of the program appears twice (before and inside the heredoc)
# Then it puts the string twice (* 2) and puts 2
puts <<2*2,2
# Quines are programs that print their own source code
# This program is a quine that explains how some Ruby quines work

# This first one uses a heredoc with 2 as the delimiter
# The beginning of the program appears twice (before and inside the heredoc)
# Then it puts the string twice (* 2) and puts 2
puts <<2*2,2
2

# eval a string that prints the beginning of the program and then inspects _
# Assign the string to _ so it inspects itself.
eval _="print '\n# eval a string that prints the beginning of the program and then inspects _\n# Assign the string to _ so it inspects itself.\neval _=';p _"

# String starts with the beginning of the program, uses the c format specifier
# to turn ords into chars (34 for double quote and 10 for newline), and s
# for the string itself, and includes the end of the program
# Assign the string to a variable and then format print it with itself.
_="
# String starts with the beginning of the program, uses the c format specifier
# to turn ords into chars (34 for double quote and 10 for newline), and s
# for the string itself, and includes the end of the program
# Assign the string to a variable and then format print it with itself.
_=%c%s%c; printf _,34,_,34,10%c
"; printf _,34,_,34,10

# String starts with the beginning of the program, uses p format specifier to
# inspect the arg, and ends with a percent-escaped end of the program
# Assign the string to a variable, and format it with itself
_="# String starts with the beginning of the program, uses p format specifier to\n# inspect the arg, and ends with a percent-escaped end of the program\n# Assign the string to a variable, and format it with itself\n_=%p;puts _%%_\n";puts _%_