BernardK

BernardK

Programming Ruby 3.2 (5th Edition): B1.0 page 205, Only then do we create

@noelrappin

page 205, paragraph after the code, line 2 :

then blocks at Ractor.receive. Only then do we create the reading ractor

Because of “Only then” I thought that creating the second Ractor could only take place when the first is waiting on receive. But the trace shows that both Ractors are created, then the blocks are scheduled.

On page 204 (par. 5, code for one, line 1) I liked “Moving down the file”, for a possible replacement of “Only then”.

Having said that, it’s impressive to see the reader sending several times without waiting for a take.

def displayWord(p_word)
    p_word.nil? ? "^nil^" : "|#{p_word}|"
end
    
puts "*** (main) about to create counter"
counter = Ractor.new(name: "counter") do
  puts ">>> ccccc in counter block"
  result = Hash.new(0)
  while (word = Ractor.receive)
    puts "ccccc in counter received word=#{displayWord(word)}"
    result[word] += 1
    puts "ccccc looping"
  end
  puts "ccccc in counter while ended word=#{displayWord(word)}"
  result
end

puts "*** (main) about to create reader"
Ractor.new(counter, name: "reader") do |counter|
  puts ">>> rrrrr in reader block"
  File.foreach("testfile") do |line|
    puts "rrrrr line=#{line}"
    line.scan(/\w+/) do |word|
      puts "rrrrr about to send word=#{displayWord(word)}"
      counter.send(word.downcase)
      puts "rrrrr after send"
    end
  end
  puts "rrrrr about to send nil"
  counter.send(nil)
end

puts "*** (main) about to take counter"
counts = counter.take
counts.keys.sort.each { |k| print "#{k}:#{counts[k]} " }
puts
% ruby -w ractor_word_count_flipped.rb 
*** (main) about to create counter
<internal ... experimental ...
*** (main) about to create reader
*** (main) about to take counter
>>> ccccc in counter block
>>> rrrrr in reader block
rrrrr line=This is line one
rrrrr about to send word=|This|
rrrrr after send
rrrrr about to send word=|is|
rrrrr after send
rrrrr about to send word=|line|
ccccc in counter received word=|this|
...

First Post!

noelrappin

noelrappin

Author of Modern Front-End Development for Rails

Thanks!

Where Next?

Popular Pragmatic Bookshelf topics Top

New
iPaul
page 37 ANTLRInputStream input = new ANTLRInputStream(is); as of ANTLR 4 .8 should be: CharStream stream = CharStreams.fromStream(i...
New
mikecargal
Title: Hands-on Rust: question about get_component (page 295) (feel free to respond. “You dug you’re own hole… good luck”) I have somet...
New
JohnS
I can’t setup the Rails source code. This happens in a working directory containing multiple (postgres) Rails apps. With: ruby-3.0.0 s...
New
alanq
This isn’t directly about the book contents so maybe not the right forum…but in some of the code apps (e.g. turbo/06) it sends a TURBO_ST...
New
jskubick
I think I might have found a problem involving SwitchCompat, thumbTint, and trackTint. As entered, the SwitchCompat changes color to hol...
New
brunogirin
When installing Cards as an editable package, I get the following error: ERROR: File “setup.py” not found. Directory cannot be installe...
New
brunogirin
When running tox for the first time, I got the following error: ERROR: InterpreterNotFound: python3.10 I realised that I was running ...
New
dsmith42
Hey there, I’m enjoying this book and have learned a few things alredayd. However, in Chapter 4 I believe we are meant to see the “&gt;...
New
mcpierce
@mfazio23 I’ve applied the changes from Chapter 5 of the book and everything builds correctly and runs. But, when I try to start a game,...
New

Other popular topics Top

Devtalk
Reading something? Working on something? Planning something? Changing jobs even!? If you’re up for sharing, please let us know what you’...
1052 22283 402
New
AstonJ
I ended up cancelling my Moonlander order as I think it’s just going to be a bit too bulky for me. I think the Planck and the Preonic (o...
New
dimitarvp
Small essay with thoughts on macOS vs. Linux: I know @Exadra37 is just waiting around the corner to scream at me “I TOLD YOU SO!!!” but I...
New
PragmaticBookshelf
Build highly interactive applications without ever leaving Elixir, the way the experts do. Let LiveView take care of performance, scalabi...
New
foxtrottwist
A few weeks ago I started using Warp a terminal written in rust. Though in it’s current state of development there are a few caveats (tab...
New
mafinar
This is going to be a long an frequently posted thread. While talking to a friend of mine who has taken data structure and algorithm cou...
New
PragmaticBookshelf
Author Spotlight Jamis Buck @jamis This month, we have the pleasure of spotlighting author Jamis Buck, who has written Mazes for Prog...
New
husaindevelop
Inside our android webview app, we are trying to paste the copied content from another app eg (notes) using navigator.clipboard.readtext ...
New
AstonJ
If you’re getting errors like this: psql: error: connection to server on socket “/tmp/.s.PGSQL.5432” failed: No such file or directory ...
New
PragmaticBookshelf
Get the comprehensive, insider information you need for Rails 8 with the new edition of this award-winning classic. Sam Ruby @rubys ...
New

Sub Categories: