Is it possible from within shoooes to spawn a separate thread which will read from a named pipe and then print whatever is written in that name pipe into a text box? Would anyone have an example of how to set that up?
It's pretty easy to manipulate text across threads. Try this code, for example:
Shoes.app do
#text = para 'Do you like ponies?'
Thread.new do
sleep(4)
#text.text += " Of course I do!"
end
timer(2) {#text.text += "\nWhat a silly question."}
end
As to reading from a named pipe, they can be treated like any other file, with the caveat that they will block until the other side of the pipe is set up. So, either make them non-blocking or just set the other side up before you open the pipe.
Related
I have two Ruby scripts: loop.rb and event.rb. When I run event.rb while running a loop in loop.rb, the former must catch the latter and change its behaviour.
There are many hacks that I can use; for example, loop.rb watches some env-var, and event.rb changes it. But I feel it a bit dirty.
What is the right way to send message from one Ruby script to another in Linux?
I think best option would be to use ZeroMQ:
https://github.com/zeromq/rbzmq
require "zmq"
context = ZMQ::Context.new(1)
puts "Opening connection for READ"
inbound = context.socket(ZMQ::UPSTREAM)
inbound.bind("tcp://127.0.0.1:9000")
outbound = context.socket(ZMQ::DOWNSTREAM)
outbound.connect("tcp://127.0.0.1:9000")
p outbound.send("Hello World!")
p outbound.send("QUIT")
loop do
data = inbound.recv
p data
break if data == "QUIT"
end
I'm futzing with a lesson over on Codecademy, pretty basic but the lesson prompts the user for a string and then prompts them for words to hide from the string. I've already finished with the lesson but I wanted to try messing with it outside of the lesson.
What I'm finding is the following script will run to completion in the lesson's scripting and interpreter area but if I try to run the same script over at say labs.codecademy.com or repl.it
I'll get prompted for the first question and if I enter a string containing an apostrophe it won't go on to the next prompt. I'm not getting an error, but eventually I'll get a "This program is taking too long to finish" pop up.
Here's the script:
puts "Tell me something."
text = gets.chomp
puts "What would you like me to forget?"
redact = gets.chomp
words = text.split(" ")
words.each { |text|
if redact.include? text
print "REDACTED "
else
print text + " "
end
}
So for example if you were to enter I really like blueberry pie that passes, but if you were to enter They've told me I should try the blueberry pie the program gets hung up.
I'm a complete novice when it comes to Ruby, but is there a way to have gets process that sort of punctuation? Or is that not the right way to go about it? Or is it just the environment I'm trying to run this program in?
IO.gets is a system-level call: http://apidock.com/ruby/IO/gets
it well read from STDIN (standard input) which is the text that you type in a terminal window: http://en.wikipedia.org/wiki/Standard_streams
browsers per-se don't have this and it might depend on the implementation of the web-based console about how they handle calls like that. usually, there are known limitations (like this one).
as #BroiStatse pointed out, it might as well be a bug in in their browser-based implementation.
I've been looking for this answer in the internet for a while and have found other people asking the same thing, even here. So this post will be a presentation of my case and a response to the "solutions" that I have found.
I am such new in Ruby, but for learning purposes I decided to create a gem, here.
I am trying to implement a keyboard navigation to this program, that will allow the user use short-cuts to select what kind of request he want to see. And in the future, arrow navigations, etc.
My problem: I can't find a consistent way to get the keyboard events from the user's console with Ruby.
Solutions that I have tried:
Highline gem: Seems do not support this feature anymore. Anyway it uses the STDIN, keep reading.
STDIN.getch: I need to run it in a parallel loop, because at the same time that the user can use a short-cut, more data can be created and the program needs to show it. And well, I display formated text in the console, (Rails log). When this loop is running, my text lost the all the format.
Curses: Cool but I need to set position(x,y) to display my text every time? It will get confusing.
Here is where I am trying to do it.
You may note that I am using "stty -raw echo" (turns raw off) before show my text and "stty raw -echo" (turns raw on) after. That keeps my text formated.
But my key listener loop is not working. I mean, It works in sometimes but is not consistent. If a press a key twice it don't work anymore and sometimes it stops alone too.
Let me put one part of the code here:
def run
# Two loops run in parallel using Threads.
# stream_log loops like a normal stream in the file, but it also parser the text.
# break it into requests and store in #requests_queue.
# stream_parsed_log stream inside the #requests_queue and shows it in the screen.
#requests_queue = Queue.new
#all_requests = Array.new
# It's not working yet.
Thread.new { listen_keyboard }
Thread.new { stream_log }
stream_parsed_log
end
def listen_keyboard
# not finished
loop do
char = STDIN.getch
case char
when 'q'
puts "Exiting."
exit
when 'a'
#types_to_show = ['GET', 'POST', 'PUT', 'DELETE', 'ASSET']
requests_to_show = filter_to_show(#all_requests)
command = true
when 'p'
#types_to_show = ['POST']
requests_to_show = filter_to_show(#all_requests)
command = true
end
clear_screen if command
#requests_queue += requests_to_show if command
command = false
end
end
I need a light in my path, what should I do?
That one was my mistake.
It's just a logic error in another part of code that was running in another thread so the ruby don't shows the error by default. I used ruby -d and realized what was wrong. This mistake was messing my keyboard input.
So now it's fixed and I am using STDIN.getch with no problem.
I just turn the raw mode off before show any string. And everything is ok.
You can check here, or in the gem itself.
That's it.
Having looked at this question, I have the following code:
$/ = "\0"
answer = STDIN.gets
Now, I was hoping that this would allow the user to:
enter a multi-line input, terminating by pressing Ctrl-D.
enter a single line input, terminating by pressing Ctrl-D.
enter a "nothing" input, terminating by pressing Ctrl-D.
However, the behaviour I actually see is that:
The user can enter a multi-line input fine.
The user can not enter a single line input, unless they hit Ctrl-D twice.
The user can enter a "nothing" input if they hit Ctrl-D straight away.
So, why does the single line situation (i.e. if the user has entered some text but no newline and then hit Ctrl-D) require two presses of Ctrl-D? And why does it work then if the user enters nothing? (I have noted that if they enter nothing and hit Ctrl-D, I don't get an empty string but the nil class - I discovered this when trying to call .empty? on the result, since it suddenly failed horribly. If there is a way to get it to return an empty string as well, that would be nice. I prefer checking .empty? to ==, and don't particularly want to define .empty? for the nil class.)
EDIT: Since I really would like to know the "correct way" to do this in Ruby, I am offering a bounty of 200 rep. I will also accept answers that give another way of entering terminal multi-line input with a sensible "submit" procedure - I will be the judge of 'suitable'. For example, we're currently using two "\n"s, but that's not suitable, as it blocks paragraphs and is unintuitive.
The basic problem is the terminal itself. See many of the related links to the right of your post. To get around this you need to put the terminal in a raw state. The following worked for me on a Solaris machine:
#!/usr/bin/env ruby
# store the old stty settings
old_stty = `stty -g`
# Set up the terminal in non-canonical mode input processing
# This causes the terminal to process one character at a time
system "stty -icanon min 1 time 0 -isig"
answer = ""
while true
char = STDIN.getc
break if char == ?\C-d # break on Ctrl-d
answer += char.chr
end
system "stty #{old_stty}" # restore stty settings
answer
I'm not sure if the storing and restoring of the stty settings is necessary but I've seen other people do it.
When reading STDIN from a terminal device you are working in a slightly different mode to reading STDIN from a file or a pipe.
When reading from a tty Control-D (EOF) only really sends EOF if the input buffer is empty. If it is not empty it returns data to the read system call but does not send EOF.
The solution is to use some lower level IO and read a character at a time. The following code (or somethings similar) will do what you want
#!/usr/bin/env ruby
answer = ""
while true
begin
input = STDIN.sysread(1)
answer += input
rescue EOFError
break
end
end
puts "|#{answer.class}|#{answer}|"
The results of running this code with various inputs are as follows :-
INPUT This is a line<CR><Ctrl-D>
|String|This is a line
|
INPUT This is a line<Ctrl-D>
|String|This is a line|
INPUT<Ctrl-D>
|String||
I am writing a web based debugger for Ruby, but in order to do this I need to be able to call the Ruby debugger from within a Ruby program on the server side. Has this ever been done? Is this even possible?
The end product being built will allow Ruby code to be edited, executed and stepped through using just a web browser. The ruby code that is to be debugged will be "eval"ed on the server side.
I have since been pointed in the right direction by one of the stackoverflow users who has suggested using popen or expect. I have tried both of these now but have encountered the following problems:
popen: When waiting for the console you have to use a timeout block to signal the end of the debug console's output (The command line terminal can detect this, so why can't ruby).
expect: In the program below the debugger inputs get out of sync with the debugger. Why is that?
require 'pty'
require 'expect'
$expect_verbose = true
PTY.spawn("rdebug deb.rb") do |from_debugger, to_debugger, pid|
a=nil
while ( a != "end" ) do
from_debugger.expect(/\(rdb:1\)/ ) do |input|
a = gets
to_debugger.puts( a + "\n" )
end
from_debugger.flush
end
end
I think you could make use of ruby-debug. I would imagine this as opening the same script on the server-side, and sending keystrokes to it. I think this is how I'd do it.
Think about it this way: the client pastes his code in your form. Optionally, he may click on some button that places a breakpoint on some line. Then he submits the whole thing. On server side, you process that form, and create a .rb file with the contents of the form. At the line where he put the breakpoint, you insert a debugger call. Then you run :
ruby client_script.rb
and this will stop the process once it reaches the debugger line. I would suggest you do all of this with Expect for Ruby or whatever. So, when the client presses step over on the page or inspect whatever variable, you send keystrokes to the process you spawned.
For example, if he wants to inspect the value of the variable x, you'd send this to the process:
p x
and you'd have to capture that output and send it back to the client's browser. Expect is kind of like popen , but a bit better.
I finally figured out how to do this using expect:
require 'pty'
require 'expect'
PTY.spawn("rdebug deb.rb") do |output,input,pid|
while true do
begin
buffer = ""
puts "-------"
puts output.readpartial(1024,buffer) until buffer =~ /\(rdb:1\)/
a = gets
input.puts a
rescue
break
end
end
end