Is there a way to automatically execute code when binding.pry is encountered?
For example, if I want to execute puts "Hey, I'm debugging!" every time binding.pry is called?
I felt like having a look at the code and found something that might be useful, you either have to add it to the gemfile or you might be able to add it to your .pryrc (I don't know if this gets called from binding.pry or not). From github there appears to be:
# #example Adding a hook for the `:before_session` event.
Pry.config.hooks.add_hook(:before_session, :say_hi) do
puts "hello"
end
From the pry github hooks file.
EDIT: Here's an example to register the hook and execute it (i.e. init your app) from another part of the pry github hooks file:**
my_hook = Pry::Hooks.new.add_hook(:before_session, :say_hi) { puts "hi!" }
my_hook.exec_hook(:before_session) #=> OUTPUT: "hi!"
Related
Is there a Ruby Cucumber test hook for at_start? I tried at_start and it didn't work.
I have something like this in support/hooks.rb and I want to print a single global message before any of the tests start:
Before do
print '.'
end
at_exit do
puts ''
puts 'All Cucumber tests finished.'
end
It seems like if they have an at_exit hook, they should have a before-start hook as well right?
There is some documentation for "global hooks" at https://github.com/cucumber/cucumber/wiki/Hooks
You don't need to wrap it in any special method such as Before or at_exit. You just execute the code at the root level in any file contained in the features/support directory, such as env.rb. To copy and paste the example they've given:
# these following lines are executed at the root scope,
# accomplishing the same thing that an "at_start" block might.
my_heavy_object = HeavyObject.new
my_heavy_object.do_it
# other hooks can be defined in the same file
at_exit do
my_heavy_object.undo_it
end
They also give an example of how to write a Before block that gets executed only once. Basically you have this block exit if some global variable is defined. The first time the block is run, the global variable is defined which prevents it from being executed multiple times. See the "Running a Before hook only once" section on that page I linked.
I'll show an example of what I'm trying to do.
child.rb
require 'parent'
class Child < Parent
...
end
parent.rb
class Parent
puts __FILE__
...
end
running this (e.g. in IRB):
require 'child'
child=Child.new
returns this:
/path/to/parent.rb
but i'm really trying to get the file child.rb instead.
How can i do this without moving the puts __FILE__ in to the child class directly?
There is no way in Ruby to get what you are asking for. Perhaps if you explained why you want this—what you are trying to accomplish—then I (or someone else) could help you further. As it stands you seem to be asking an XY problem.
Although it's not always the "file that required me", you can use $0 in this case instead of __FILE__ to get "the root file that is running" in the case when you have done ruby parent.rb. Note that this will not work with IRB, however. (Inside IRB $0 is always "irb" or something equally unhelpful.)
Redefine require to output caller_locations.first.absolute_path before calling the original require.
you can use some backtrace method like caller_locations(1,1)[0].path or caller
I want make interactive application where user launches it and can do various task by typing commands (some kind of shell)
example:
./myapp.rb
App says Hi
Commands:
help - display help about command
open - open task
do - do action
Start>help open
open <TaskName>
opens specified task
Start>open Something
Something>do SomeAction
Success!
Something> (blinking cursor here)
I searched but couldn't find any ruby gems that I could use specially for console interaction, so I'm about to my make my own...
I looked at Thor, but that's not exactly as I want, maybe I could use it, but not sure...
it could look something like:
class Tasks
attr_reader :opened_task
desc "open <TaskName>", "opens specified task"
def open(params)
end
desc "do <ActionName>", "do specified action"
def do(params)
end
end
tasks = Tasks.new
# theoretical Console class
console = Console.new
console.addCommand("open",tasks.method(:open),"open task")
console.addCommand("do",tasks.method(:do),"do action")
console.start("%s>",[*tasks.opened_task])
so my question is, what gems I could use to make such console class? maybe someone have already made something similar?
I plan using HighLine for input/output, but any other suggestion what could I use?
What you want is a REPL – Read → Evaluate → Print Loop.
IRB, for example, implements a REPL for the Ruby language.
Here's a very simple implementation of your application's REPL:
loop do
Application::Console.prompt.display
input = gets.chomp
command, *params = input.split /\s/
case command
when /\Ahelp\z/i
puts Application::Console.help_text
when /\Aopen\z/i
Application::Task.open params.first
when /\Ado\z/i
Application::Action.perform *params
else puts 'Invalid command'
end
end
\A and \z match the start of the string and the end of the string, respectively.
You could also try ripl. (from the documentation):
Creating and starting a custom shell is as simple as:
require 'ripl'
# Define plugins, load files, etc...
Ripl.start
There is a comprehensive list of plugins for ripl as well as list of console applications using ripl on the projects website.
ok, so I made this library for creating console applications in ruby. Actually it was some while ago, but only just decided to release it. It does support auto-completion if used with HighLine and Readline.
When I wrote it there wasn't any documentation nor tests/specs, but now I made some. Still not much but for beginning should be ok.
So gem cli-console and
code is at GitHub, here's usage example
TTY is a really good gem for easily doing this sort of things. You have plenty of tools which can work alone or with the full toolKit. You can use colors, prompts, execute shell natives, interact with the screen, print tables, progressbars and many other useful elements of command lines whith the easy of a goop api.
Particularly tty-prompt is really useful for asking for user input.
A brief example for the case you proposed:
require 'tty-prompt'
require 'pastel'
prompt = TTY::Prompt.new
loop do
cmd, parms* = prompt.ask('user#machine$ ').split /\s/
case cmd
when "hola"
puts "Hola amigo " parms
when "exit"
break if prompt.yes?('Do you really want to exit?')
end
end
Take a look at cliqr ruby gem. It looks like exactly what you need. Here is the github link with a descriptive readme: https://github.com/anshulverma/cliqr
It can execute the commands directly or within a inbuilt shell.
Here is a test case from its git repo:
it 'can execute a sub action from shell' do
cli = Cliqr.interface do
name 'my-command'
handler do
puts 'base command executed'
end
action :foo do
handler do
puts 'foo executed'
end
action :bar do
handler do
puts 'bar executed'
end
end
end
end
with_input(['', 'my-command', 'foo', 'foo bar', 'foo bar help']) do
result = cli.execute %w(my-command shell), output: :buffer
expect(result[:stdout]).to eq <<-EOS
Starting shell for command "my-command"
my-command > .
base command executed
my-command > my-command.
base command executed
my-command > foo.
foo executed
my-command > foo bar.
bar executed
my-command > foo bar help.
my-command foo bar
USAGE:
my-command foo bar [actions] [options] [arguments]
Available options:
--help, -h : Get helpful information for action "my-command foo bar" along with its usage information.
Available actions:
[ Type "my-command foo bar help [action-name]" to get more information about that action ]
help -- The help action for command "my-command foo bar" which provides details and usage information on how to use the command.
my-command > exit.
shell exited with code 0
EOS
end
end
class MyAPI
def self.__is__(text)
#__is__ = text
end
def self.method_added(method)
#__help__ ||= {}
#__help__[method.to_s] = #__is__
#__is__ = nil
end
def self.help(of)
#__help__[of]
end
__is__ "open file <file>"
def open(file)
#...
end
__is__ "do X"
def do(*params)
#...
end
__is__ "calls help, use help <command>"
def help(*args, &block)
self.class.help(*args, &block)
end
end
MyAPI.new(...).pry
Or you could use pry commands, but that defeats the
turing-completeness. Help might be implemented using commands, as I'm
not sure how well my approach works out. Those methods need to be
coded defensive. I can't remember how to use class variables :-/
I'm new to Ruby, so apologies if this sounds really silly.
I can't seem to figure out how to write a "main" code and have methods in the same file (similar to C). I end up with a "main" file which loads a seperate file that has all the methods. I appreciate any guidance on this.
I spotted the following SO post but I don't understand it:
Should I define a main method in my ruby scripts?
While it's not a big deal, it's just easier being able to see all the relevant code in the same file. Thank you.
[-EDIT-]
Thanks to everyone who responded - turns out you just need to define all the methods above the code. An example is below:
def callTest1
puts "in test 1"
end
def callTest2
puts "in test 2"
end
callTest1
callTest2
I think this makes sense as Ruby needs to know all methods beforehand. This is unlike C where there is a header file which clearly list the available functions and therefore, can define them beneath the main() function
Again, thanks to everyone who responded.
#Hauleth's answer is correct: there is no main method or structure in Ruby. I just want to provide a slightly different view here along with some explanation.
When you execute ruby somefile.rb, Ruby executes all of the code in somefile.rb. So if you have a very small project and want it to be self-contained in a single file, there's absolutely nothing wrong with doing something like this:
# somefile.rb
class MyClass
def say_hello
puts "Hello World"
end
end
def another_hello
puts "Hello World (from a method)"
end
c = MyClass.new
c.say_hello
another_hello
It's not that the first two blocks aren't executed, it's just that you don't see the effects until you actually use the corresponding class/method.
The if __FILE__ == $0 bit is just a way to block off code that you only want to run if this file is being run directly from the command line. __FILE__
is the name of the current file, $0 is the command that was executed by the shell (though it's smart enough to drop the ruby), so comparing the two tells you precisely that: is this the file that was executed from the command line? This is sometimes done by coders who want to define a class/module in a file and also provide a command-line utility that uses it. IMHO that's not very good project structure, but just like anything there are use cases where doing it makes perfect sense.
If you want to be able to execute your code directly, you can add a shebang line
#!/usr/bin/env ruby
# rest of somefile.rb
and make it executable with chmod +x somefile.rb (optionally rename it without the .rb extension). This doesn't really change your situation. The if __FILE__ == $0 still works and still probably isn't necessary.
Edit
As #steenslag correctly points out, the top-level scope in Ruby is an Object called main. It has slightly funky behavior, though:
irb
>> self
=> main
>> self.class
=> Object
>> main
NameError: undefined local variable or method `main' for main:Object
from (irb):8
Don't worry about this until you start to dig much deeper into the language. If you do want to learn lots more about this kind of stuff, Metaprogramming Ruby is a great read :)
No there isn't such structure. Of course you can define main function but it won't be called until you do so. Ruby execute line by line so if you want to print 'Hello World' you simply write:
puts 'Hello World'
The question that you mentioned is about using one file as module and executable, so if you write
if __FILE__ == $0
# your code
end
It will be called only if you run this file. If you only require it in other file then this code will never run. But IMHO it's bad idea, better option is using RubyGems and there add executables.
Actually there is a main, but it is not a method; it's the top-level object that is the initial execution context of a Ruby program.
class Foo
p self
end
#=> Foo
p self
#=> main
def foo
p self
end
foo
#=> main
There is no magic main function in Ruby. See http://en.wikipedia.org/wiki/Main_function#Ruby
If you wish to run Ruby scripts like C compiled files, do the following:
#!/usr/bin/env ruby
puts "Hello"
and then chmod a+x file_name.rb. Everything that is below the first line will be run, as if it was contents of main in C. Of course class and function definitions won't give you any results until they are instantiated/invoked (although the code inside class definitions is actually evaluated, so you could get some output but this is not expected in normal circumstances).
Another way to write main() method is:
class HelloWorld
def initialize(name)
#name = name
end
def sayHello()
print "Hello ##name!"
end
end
def main()
helloWorld = HelloWorld.new("Alice")
helloWorld.sayHello
end
main
Can I drop to an IRB prompt from a running Ruby script?
I want to run a script, but then have it give me an IRB prompt at a point in the program with the current state of the program, but not just by running rdebug and having a breakpoint.
Pry (an IRB alternative) also lets you do this, in fact it was designed from the ground up for exactly this use case :)
It's as easy as putting binding.pry at the point you want to start the session:
require 'pry'
x = 10
binding.pry
And inside the session:
pry(main)> puts x
=> 10
Check out the website: http://pry.github.com
Pry let's you:
drop into a session at any point in your code
view method source code
view method documentation (not using RI so you dont have to pre-generate it)
pop in and out of different contexts
syntax highlighting
gist integration
view and replay history
open editors to edit methods using edit obj.my_method syntax
A tonne more great and original features
you can use ruby-debug to get access to irb
require 'rubygems'
require 'ruby-debug'
x = 23
puts "welcome"
debugger
puts "end"
when program reaches debugger you will get access to irb.
apparently it requires a chunk of code to drop into irb.
Here's the link (seems to work well).
http://jameskilton.com/2009/04/02/embedding-irb-into-your-ruby-application
require 'irb'
module IRB
def self.start_session(binding) # call this method to drop into irb
unless #__initialized
args = ARGV
ARGV.replace(ARGV.dup)
IRB.setup(nil)
ARGV.replace(args)
#__initialized = true
end
workspace = WorkSpace.new(binding)
irb = Irb.new(workspace)
#CONF[:IRB_RC].call(irb.context) if #CONF[:IRB_RC]
#CONF[:MAIN_CONTEXT] = irb.context
catch(:IRB_EXIT) do
irb.eval_input
end
end
end
This feature is available from Ruby 2.4. You can just use binding.irb
E.g.
require 'irb'
a = 10
binding.irb
puts a
If you run above code, you will get irb console, so that you can inspect values of local variables and anything else that is in scope.
Source: http://blog.redpanthers.co/new-binding-irb-introduced-ruby-2-4/
Ruby commit: https://github.com/ruby/ruby/commit/493e48897421d176a8faf0f0820323d79ecdf94a
Just add this line to where you want the breakpoint:
require 'ruby-debug';debugger
but i suggest use pry instead of irb, which is super handy, insert the following line instead:
require 'pry'; binding.pry
I'm quite late to the game but if you're loading a script from within irb/pry already, a simple raise also works to pop you back out to the irb/pry prompt. I use this quite often when writing one off scripts within the rails console.