Try Ruby is a interactive shell that quickly and whimsically teaches the Ruby programming language. Originally _why's idea, it has been recreated from the ground up by Rubyists who have a passion for Ruby and for teaching their fellow (wo)man how to program.
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(is now 1.9-ready and hosted using 1.9. Please note this is beta software.)

What is all this?

The best way to learn a thing is to try it!

Try out Ruby. Learn about it. Be guided on a veritable carnival ride of Ruby wondrousness.

When you come out the other side, you'll likely find that

  1. Your computer understands what you're saying! And you don't have much trouble speaking its dialect.
  2. You have some skill in climbing about on your computer's command line.

It was originally made by a fellow named _why. But he disappeared. So some other folks have rebuilt it. (See the license for details.)

You can help!

It would be wonderful to have some help building this. Here's some descriptions of what's going on.

What is /irb.cgi?

After _why's disappearance, the only part of the TryRuby implementation that wasn't able to be recovered from is the /irb file (or /irb.cgi currently, you can change the name of the file used in js/irb.js). This script should:

  • Take one GET param cmd, which will contain a single line of Ruby to run. It can also be !INIT!IRB, which is called at the start of the session. The current implementation of irb.cgi ignores this. reset should also do something special (but doesn't at the moment).
  • Return the output, optionally formatted using normal shell escapes (eg \033[1;33mThis appears orange)

The output has four main formats for returning a result, error output, javascript function and line continuation. This is used by the help system so that it can detect when a user has entered the next step for the tutorial.

Output results should be formatted with a "=> " at the front of the output. For example: /irb.cgi?cmd=3*4 should output => 12. Shell escape codes can be used to give the output different colors, for example => \033[1;20m12. This will automatically be removed when used with the help system. Note that you don't and shouldn't terminate these shell escapes with \033[m (like with a normal shell).

Standard output should not be prefixed by '=>', so /irb.cgi?cmd=puts(44) should output 44\n=> nil. Here 44 is output, and nil is returned. Again shell escapes can be used.

Errors should be formated just like standard output, but should have no return. For example, /irb.cgi?cmd=non_existant_function should output something like

\033[1;33mNameError: undefined local variable or method
`non_existant_function' for main:Object".

Javascript functions (such as Popup.goto) should use the format \033[1;JsmJAVASCRIPT CODE\033[m. The javascript code will then be run. For example, /irb.cgi?cmd=Popup.goto("") should output \033[1;JSmwindow.irb.options.popup_goto("")\033[m.

Finally, if the command isn't finished (eg def myfunc), then ".." should be returned. Eg /irb.cgi?cmd=def%20myfunc should return "..".

How this works with the help system

The help system works with the file /tutorials/intro.html. There is a

section for each part of the tutorial. Most of it is just the text for that part of the tutorial. However, there is also a
section. If this matches against the output for a command, then the tutorial will go to the next step.

When the class is "answer", then it will match against lines beginning with =>. So <div class="answer">\d+</div> will match any code that returns a number. Other output can be shown as well, eg someoutput\n=> 42 will match this. The exact regexp is ^\s*=> match_regex_from_help\s*$. So the line must be an exact match, other than spaces and the initial =>

When the class is "stdout", the match must work on a complete line. Eg <div class="stdout">hello</div> will match hello, or start\n hello\ngoodbye (leading spaces are ignored, and multiple lines are searched. The exact regex is ^\s*match_regex_from_help$

As a special case, if the tutorial expects that a command isn't finished (such as with def myfunc), then <div class="stdout">..</div> will be used. This is changed from the original implementation _why used, which was <div class="stdout"></div> as I couldn't get it to work like that.

Another special case, if the return should some javascript code, then something like <div class="stdout">\033\[1;JSm.*popup_goto\(.*\)\033\[m.*</div> will be used.

Current Implementation

The current implementation doesn't use persistent processes like irb. What it does is it stores all previous successfully run commands in session['previous_commands'], and runs them all first (disabling stdout). Then it will finally run the command. It uses a primitive method of detecting incomplete statements (with the function unfinished_statement?) and when a incomplete statement is finished (finished_statement?). The current nesting level (for example, entering "class X" on one line and pressing return will have a nesting level of 2) is stored in $session['nesting_level']. All the lines of the current incomplete statement are stored in $session['current_statement'].

To work with javascript functions, a special class JavascriptResult was written, with one accessor, :js. If the result of an eval returns this object, then the output will be formatted in the javascript method.

The sessions are now stored in a tmp folder. For the time being it is within the htdoc path. I know this is bad. I have included an index.html that redirects you back to the home page in the mean time. Ideally, I need to put this some place like /var/logs/tryruby.

From there I will see about the viability of making this use the r bridge so you can have ruby to R lessons. :-)