sandbox.rb
Branches > main > 149093b > files / nvim / pack / plugins / opt / conjure / dev / ruby / sandbox.rb
# Should be able to evaluate all statements.
# From https://www.ruby-lang.org/en/about/
# - Seeing Everything as an Object
5.times { print "We *love* Ruby -- it's outrageous!" }
# This should result in an error; undefined method 'plus'
5.plus 3
5+ 3 # 8
5 + 3 # 8
# form-node? can handle nested binary expressions but you must put
# your cursor on the right-most number or operator.
5 + 4 + 3 + 2 + 1 # 15
0.5 + 4 + 3 + 2 + 1 # 10.5
2 * 7 / 3 + 9 # 13
x = 2 * 7 / 3 + 9 # (out) x = 2 * 7 / 3 + 9
# => 13
puts 2 * 7 / 3 + 9
aNum = Numeric.new
# This should result in an error; undefined method '+'
aNum + 2
# After assignment, the '+' method is available.
aNum = 2 # 2
aNum + 2.0 # 4.0
aNum + 2 # 4
# - Ruby’s Flexibility
# Add a new method to an existing class.
class Numeric
def plus(x)
self.+(x)
end
end # :plus
# 'plus' and '+' are methods of a Numeric.
y = 5.plus 6
5.plus 6 # 11
5.+ 6 # 11
# form-node? recognizes the arguments of a function.
6 * 17.2 / 0.2 # 515.9999999999999
y = 5.plus 6 * 17.2 / 0.2
# y = 520.9999999999999
aNum
# => 2
aNum.plus 3 # 5
# - Blocks: a Truly Expressive Feature
search_engines =
%w[Google Yahoo MSN].map do |engine|
"http://www." + engine.downcase + ".com"
end
# search_engines = ["http://www.google.com", "http://www.yahoo.com", "http://www.msn.com"]
# - Ruby and the Mixin
# Modules are collections of methods.
class MyArray
end
MyArray.methods()
# [:allocate,
# :superclass,
# :subclasses,
# :attached_object,
# ...
# :!=,
# :__id__,
# :instance_eval,
# :instance_exec]
MyArray.methods(false) # []
MyArray.instance_methods()
# [:pretty_print_cycle,
# :pretty_print_instance_variables,
# :pretty_print_inspect,
# ...
# :!=,
# :__id__,
# :instance_eval,
# :instance_exec]
MyArray.instance_methods(false) # []
# Mixin some stuff.
class MyArray
include Enumerable
end
# Can we tell how many methods are added when we include from mixin?
Enumerable.methods(false) # []
Enumerable.instance_methods(false)
# [:drop,
# :drop_while,
# :cycle,
# ...
# :zip,
# :take,
# :take_while]
MyArray.methods()
# [:allocate,
# :superclass,
# :subclasses,
# ...
# :!=,
# :__id__,
# :instance_eval,
# :instance_exec]
MyArray.methods(false) # []
MyArray.instance_methods()
# [:drop,
# :drop_while,
# :cycle,
# ...
# :zip,
# :take,
# :take_while, <<--- From here and above are from Enumerable.
# :pretty_print_cycle,
# :pretty_print_instance_variables,
# :pretty_print_inspect,
# ...
# :!=,
# :__id__,
# :instance_eval,
# :instance_exec]
MyArray.instance_methods(false) # []
# End of From https://www.ruby-lang.org/en/about/
# Incorrect array expression
3 4 5]
# => (error) <internal:kernel>:168:in 'Kernel#loop': (irb):89: syntax errors found (SyntaxError)
[3 4 5]
# => (error) <internal:kernel>:168:in 'Kernel#loop': (irb):90: syntax errors found (SyntaxError)
# Correct array expression
[3, 4, 5] # [3, 4, 5]
# Block comments
# - https://docs.ruby-lang.org/en/master/syntax/comments_rdoc.html
=begin
This is commented out.
class Foo
end
=end
# =begin and =end can not be indented, so this is a syntax error:
class Foo
=begin
Will not work
=end
end
# frozen strings
# https://stackoverflow.com/a/37799399
# `# frozen_string_literal: true` is supposed to make all string literals frozen.
# This works only if the magic comment is in the first comment section of a file.
var = 'hello'
var.frozen? # false
var.freeze()
var.frozen? # true
var << " not" # (error) (irb):29:in '<main>': can't modify frozen String: "hello" (FrozenError)
var2 = -var
var2.frozen? # true
var2 << " not" # (error) (irb):111:in '<main>': can't modify frozen String: "hello" (FrozenError)
var3 = +var
var3.frozen? # false
var3 << " not" # "hello not"
# From Ruby in Twenty Minutes
# - https://www.ruby-lang.org/en/documentation/quickstart/
puts "Hello World"
3 ** 2
Math.sqrt(9)
a = 3 ** 2
b = 4 ** 2
Math.sqrt(a+b)
def hi
puts "Hello World!"
end
# - The Brief, Repetitive Lives of a Method
hi # eval word or selection
hi() # eval current-form
def hi(name)
puts "Hello #{name}!"
end
hi("Matz")
# - Holding Spots in a String
def hi(name = "World")
puts "Hello #{name.capitalize}!"
end
# Eval these with selections:
hi "chris"
# (out) hi "chris"
hi
# (out) Hello World!
# - Evolving Into a Greeter
class Greeter
def initialize(name = "World")
@name = name
end
def say_hi
puts "Hi #{@name}!"
end
def say_bye
puts "bye #{@name}, come back soon."
end
end
greeter = Greeter.new("Pat")
greeter.say_hi
greeter.say_bye
# This should be an error.
greeter.@name
# - Under the Object’s Skin
Greeter.instance_methods
Greeter.instance_methods()
Greeter.instance_methods(false) # [:say_hi, :say_bye]
greeter.respond_to?("name") # false
greeter.respond_to?("say_hi") # true
greeter.respond_to?("to_s") # true
# - Altering Classes—It’s Never Too Late
class Greeter
attr_accessor :name
end
greeter = Greeter.new("Andy")
# Access attribute
greeter.respond_to?("name") # true
# Set attribute
greeter.respond_to?("name=") # true
# Same as when evaluated with "()".
greeter.say_hi
# This should update the name attribute.
greeter.name="Betty"
greeter
greeter.name
greeter.say_hi
# - Cycling and Looping—a.k.a. Iteration
class MegaGreeter
attr_accessor :names
# Create the object
def initialize(names = "World")
@names = names
end
# Say hi to everybody
def say_hi
if @names.nil?
puts "..."
elsif @names.respond_to?("each")
# @names is a list of some kind, iterate!
@names.each do |name|
puts "Hello #{name}!"
end
else
puts "Hello #{@names}!"
end
end
# Say bye to everybody
def say_bye
if @names.nil?
puts "..."
elsif @names.respond_to?("join")
# Join the list elements with commas
puts "Goodbye #{@names.join(", ")}. Come back soon!"
else
puts "Goodbye #{@names}. Come back soon!"
end
end
end
mg = MegaGreeter.new
# Evaluate with selection:
mg.say_hi
# (out) Hello World!
# => nil
mg.say_bye
# (out) Goodbye World. Come back soon!
# => nil
mg.names # "World"
mg.names.respond_to?("each") # false
mg.names.respond_to?("join") # false
# Change the name to an array of names
mg.names = ["Albert", "Brenda", "Charles", "Dave", "Engelbert"]
# Evaluate with selection:
mg.say_hi
# (out) Hello Albert!↵Hello Brenda!↵Hello Charles!↵Hello Dave!↵Hello Engelbert!
# => ["Albert", "Brenda", "Charles", "Dave", "Engelbert"]
#
mg.say_bye
# (out) Goodbye Albert, Brenda, Charles, Dave, Engelbert. Come back soon!
# => nil