Pry goes into interactive mode if it encounters an exception (eg if you just put an undefined variable 'x' at the end of the script).
(Also if, inside the script itself you require 'pry' and put binding.pry at the point you want to go interactive at.)
But I'm wondering: Is there's some kind of flag/option/argument thingy that I can add to the pry example.rb command when I enter it at the command prompt, so it will go interactive when it reaches the end of executing any example.rb script, regardless of what's inside? (Assuming no exceptions before the end, of course.)
(This would obviously be especially useful for use with editors that you can run external programs from like Notepad++, see this and this.)
Not yet, but file an issue and i'll add it :)
Related
Is it possible to run irb, pass it a .rb file that gets automatically executed, and have irb stay running in interactive mode?
On Windows, I have a file called checkme.bat that basically does the following:
irb checkme.rb
The problem right now is that when I run checkme.bat, irb executes the program file but then simply exits, leaving me back at the command line.
One way to do this is to use pry and add the line binding.pry at the point in your script where you want to bail out into the repl.
x = 3
puts "Hello!"
binding.pry
Then you can run your script with pry and it'll let you examine what's going on.
~> pry d.rb
Hello
[1] pry(main)> x
=> 3
[2] pry(main)>
I'm not quite sure but on Windows when you execute a .rb file it instantly closes, try using gets at the end of the program.
I'm using a helper script to execute rspec tests.
command = "rake spec #{path} #{scope}"
output = `#{command}`
puts output
This works fine, except that I lose all the colors from the rake rspec output. The appropriate ANSI codes do not appear to be contained within the output string.
How can I execute a process so that it returns output which includes the text color?
Kernel.exec() gets me the solution I want (colored rspec output), but it does so by replacing my ruby script process with the rspec process. That means I can't do anything with the output or run anything after the rspec call.
That's acceptable in my particular situation, but less than ideal as a general solution. So I'd like a better answer if available.
RSpec will disable colour if it is not writing to a tty (i.e. the console).
In case of RSpec you can force colouring by rspec --tty or via rake by rake spec SPEC_OPTS=' --tty'.
See also Ruby popen3 and ANSI colour
However this solution is still specific to Rspec. I'd be interested to hear a general one.
Turns out it's possible to run commands in a pseudo terminal via the PTY module in order to preserve a user facing terminal-like behaviour. Credits go to the creator of the tty-command gem (see this issue) who implemented this behaviour in his gem:
require 'tty-command'
cmd = TTY::Command.new(pty: true)
cmd.run('rake', 'rspec')
Keep in mind that using a pseudo terminal may have unwanted side effects, such as certain git commands using a pager which will essentially cause commands to hang. So introducing the functionality might be a breaking change.
If you don't want to replace your ruby process with that command, use Kernel.system() or Kernel.spawn() instead of a Kernel.exec(). Both of them execute your command in a subshell, system waits for the subprocess to finish, spawn returns its pid and you have to wait by yourself using Process.wait pid.
command = "rake spec #{path} #{scope}"
system(command)
or
command = "rake spec #{path} #{scope}"
pid = spawn(command)
# Some other stuff here
Process.wait pid
I was trying to figure out how to work the command line switch -r.
My understanding is that the code is typed out as follows:
ruby -r*nameOfRequired*
I am finding that this is not the case. When I type out the above and press enter, the terminal expects an "end of input syntax" and does not continue.
What am I missing? Does there need to be a space in between the switch and the name of the required file?
Please and thank you!
EDIT:
I am currently reading "The Well Grounded Rubyist" by David A. Black, and I came up with this question while reading the section on command line switches.
Having said that, I created a "test.rb" file, containing:
puts Date.today
Then, in the terminal, I typed out:
ruby -r date
I thought this would 'require' the date module, and then enable me to run the "test.rb" file, using ruby test.rb (given that I am in the correct directory).
Instead, the terminal cursor moves to a newline, expecting more input. Let me know if I need to clarify anything else. Thanks!
If you just type ruby -rmodule, then Ruby will load the module and wait for you to type the main program that requires that module.
If you just want to run the module and do nothing else, you can do do rubyfull-path-to-module without the -r, or ruby -rmodule -e exit, or ruby -rmodule </dev/null, or similar.
In general, the ruby command does not record any state from one run to the next, so you need to tell it every thing that it needs to know whenever you run it.
Whenever you run it, you need to tell it the main program to run or else it will expect you to type that program on the standard input. The -r does not specify the main program.
Try this:
ruby -rdate test.rb
According to ruby -h:
-rlibrary require the library, before executing your script
Without giving your script file path, it read the script from stdin.
Try following (You can omit script file path when you give -e command):
ruby -r**nameOfRequired** -e ""
I'm trying to get simple user input in Ruby, but I can't get it working. I'm using the gets method, but the program never stops to ask me for input. I'm using Sublime Text 2 as my text editor, and I run the program in it, too (if this makes a difference).
Here's my code:
puts "What is your name?"
name = gets
puts "Hello " + name + ". How are you?"
And here's the error (and output) given to me:
C:/Users/Sten Sootla/Desktop/Ruby workspace/exercise.rb:3:in `+': can't convert nil into String (TypeError)
from C:/Users/Sten Sootla/Desktop/Ruby workspace/exercise.rb:3:in `'
What is your name?
[Finished in 0.1s with exit code 1]
Why doesn't the program stop to ask me for input?
Try using $stdin.gets instead of just a plain gets, this will force the input to come from stdin
Here's how I understand it. gets and puts are instance methods of IO, and the default IOs are $stdout and $stdin.
Calls to gets/puts will only be effective if the translator is capable of handling stdout/in e.g. IRB
If you run a ruby file from bash it works too.
io_test.rb
puts gets
in bash
ruby io_test.rb
Then it will "put" into stdout whatever it "gets" from stdin.
If you want to run code within ST2, check out the SublimeREPL plugin, available through Package Control. While you can use IRB, its main Ruby interface is through pry, which is a lot more powerful. You can use it as a classic REPL (think Clojure or LISP), and you can also transfer your code from one tab into the running REPL in another tab by selection, line range, or block.
Interestingly, your code above works in IRB for me, but not pry for some reason - it's reading my $EDITOR environment variable, which is set to subl -w but failing with Errno::ENOENT: No such file or directory - subl -w. Strange...
At any rate, I highly highly recommend SublimeREPL, as it's a really powerful tool, and is self-contained within ST2, so you don't have to keep flipping back and forth to your terminal, saving and reloading your programs.
How can I use irb the Ruby interpreter to test/debug my .rb files? I want to load an .rb file, let it run, and after it ends, get back to the irb prompt so I would be able to manipulate the variables which my script has built.
I tried load, require, and irb -r, but none of them worked as I would like. After the execution, when the program terminates, I get an irb prompt, but all of the variables are inaccessible. What can I do?
Not sure exactly what you want to do, but it sounds like you may want to use the "pry" gem instead.
Install the pry gem see: http://pryrepl.org
require 'pry' at the start of your program.
put binding.pry at the end of your program (or where you want to start the interactive session)
run your program.
Using pry you will have all your variables in scope.
More information see the link above, and here:
http://banisterfiend.wordpress.com/2011/01/27/turning-irb-on-its-head-with-pry/
and:
https://github.com/pry/pry/wiki/Runtime-invocation
If the variables you want are local variables, I do not think there is a way you can access them from another file.
If you just want the return value of the whole code that is on a different file, you can eval the whole content of that file within the main code and access the return value. You can access multiple values by putting them in an array or a hash at the end of the file to be evaled.
Add following code in place where you want irb to start
require 'irb'
IRB.start(__FILE__)
binding.irb
As of Ruby 2.4, placing this in your code will drop you into an irb session in the scope where it is placed.
No additional gem installs or require statements are needed.