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Weird behavior of #upcase! in Ruby


Weird behavior of #upcase! in Ruby

By : centelles
Date : November 21 2020, 01:01 AM
With these it helps In the clone documentation you can read:
code :
temp = Marshal.load(Marshal.dump(@person))


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String.methods.include?(:upcase) => false but '.upcase' is listed in ruby-doc.org

String.methods.include?(:upcase) => false but '.upcase' is listed in ruby-doc.org


By : Staideal
Date : March 29 2020, 07:55 AM
like below fixes the issue Strings have an upcase method. But String is not a string, it is a class, and classes don't have an upcase method.
If you want to know whether a particular string object has an upcase method, you should ask that string:
code :
'foo'.methods.include?(:upcase) # => true
String.instance_methods.include?(:upcase) # => true
Weird closure behavior in Ruby

Weird closure behavior in Ruby


By : Preethika
Date : March 29 2020, 07:55 AM
Hope this helps I was messing around with closures in Ruby and came across the following scenario that I can not understand. , The problem in your code boils down to this:
code :
results = [
  {a: [1, 2, 3]}, 
  {a: [4, 5, 6]},
]

funcs = []

while not results.empty?
  result = results.shift

  2.times do |i|
    val = result[:a] + [i]

    #funcs << lambda { p val }
    funcs << lambda { p result[:a] + [i] }
  end
end

funcs.each do |func|
  func.call
end

--output:--
[4, 5, 6, 0]
[4, 5, 6, 1]
[4, 5, 6, 0]
[4, 5, 6, 1]
val = "hello"
func = lambda { puts val }  #This will output 'hello', right?

val = "goodbye"
func.call

--output:--
goodbye
results = [
  {a: [1, 2, 3]}, 
  {a: [4, 5, 6]},
]

funcs = []

while not results.empty?
  result = results.shift
    ...
    ...

    funcs << lambda { p result[:a] + [i] }  #<==HERE
  end
end
results = [
  {a: [1, 2, 3]},
  {a: [4, 5, 6]},
]

funcs = []

while not results.empty?
  result = results.shift
  val = result[:a] + [1]

  funcs << lambda { p val }
end

funcs.each do |func|
  func.call
end

--output:--
[4, 5, 6, 1]
[4, 5, 6, 1]
while not results.empty?
  result = results.shift

  2.times do |i|
    val = result[:a] + [i]
    funcs << lambda { p val }
  end
end

--output:--
[1, 2, 3, 0]
[1, 2, 3, 1]
[4, 5, 6, 0]
[4, 5, 6, 1]
while not results.empty?
  result = results.shift

  2.times do |i|
    val = result[:a] + [i]

    #funcs << lambda { p val }
    funcs << lambda { p result[:a] + [i] }
  end
end
Ruby string upcase! method - uppercasechar.upcase! returns nil - bug or feature?

Ruby string upcase! method - uppercasechar.upcase! returns nil - bug or feature?


By : venkatesh DK
Date : March 29 2020, 07:55 AM
it helps some times Read this post especially the comments.
code :
  "abc".gsub!('d','') #=> nil 
Why does this Ruby code using char.upcase! fail but char = char.upcase works?

Why does this Ruby code using char.upcase! fail but char = char.upcase works?


By : Morten Andersen
Date : March 29 2020, 07:55 AM
it fixes the issue This is due to the definition of upcase! and downcase!. Here's upcase!
Very weird behavior in CSV (Ruby 2)

Very weird behavior in CSV (Ruby 2)


By : user7326267
Date : March 29 2020, 07:55 AM
I think the issue was by ths following , data.read won't change data to the csv string. You should just pass the result of data.read to CSV.parse. Or you could pass open(url) to CSV.parse directly.
code :
require 'csv'
require 'open-uri'

url = 'http://www.census.gov/popest/data/national/totals/2005/files/NST_EST2005_ALLDATA.csv'

CSV.parse(open(url)) do |row|
  area = row[4]
  population = row[5]
  puts "#{area} #{population}"
end

puts 'I am here!' # This prints no matter whether data.read is present
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