Irb, to learn more

ruby-talk
1

Here's an interesting thing you can do in irb:
irb

You can run an instance of irb within irb. How very Ruby!?
In irb you can also do this:

methods

(or my preferred approach...)
methods.sort

irb itself has some interesting abilities.

2

You can run an instance of irb within irb. How very Ruby!?

This is cool because it lets you set up a new context if you want to try
something without messing with your current context. I'm sure there are
other uses as well.

I believe you can also give each new one a name and switch between them
at will, but I'm not sure how.

In irb you can also do this:

methods

(or my preferred approach...)
methods.sort

The reason is that the top-level context of an IRB session is an Object,
so any method you can call on an object is there.

irb is awesome :smiley:

Ben

···

On Mon, Oct 15, 2007, John Joyce wrote:

3

Also you can do irb(object) and then you will be executing code in the
context of that object. In other words, you can jump into a class and
define an instance method on it directly, or jump into an instance and
toy around with its methods and instance variables all within its
context. Ctrl-D kicks you back out to the parent irb instance.

···

On Oct 14, 4:08 pm, John Joyce <dangerwillrobinsondan...@gmail.com> wrote:

Here's an interesting thing you can do in irb:
irb

You can run an instance of irb within irb. How very Ruby!?
In irb you can also do this:

methods

(or my preferred approach...)
methods.sort

irb itself has some interesting abilities.

4

There must be a way to jump in and out, leaving it running or not.
For example, start irb.
Then, create two named irb sessions inside it.
You operate at the top level, monitor the two inside irb's...

···

On Oct 14, 2007, at 8:20 PM, Grant Hutchins wrote:

On Oct 14, 4:08 pm, John Joyce <dangerwillrobinsondan...@gmail.com> > wrote:

Here's an interesting thing you can do in irb:
irb

You can run an instance of irb within irb. How very Ruby!?
In irb you can also do this:

methods

(or my preferred approach...)
methods.sort

irb itself has some interesting abilities.

Also you can do irb(object) and then you will be executing code in the
context of that object. In other words, you can jump into a class and
define an instance method on it directly, or jump into an instance and
toy around with its methods and instance variables all within its
context. Ctrl-D kicks you back out to the parent irb instance.

5

well, nobody claimed black magic, just that it is interesting and fun to play with. Sometimes people forget about the fun interesting aspects of irb.

6

John Joyce wrote:

There must be a way to jump in and out, leaving it running or not.
For example, start irb.
Then, create two named irb sessions inside it.
You operate at the top level, monitor the two inside irb's...

There's no black magic here. In the online available version of the
Pickaxe book, you can find out about this:

http://www.rubycentral.com/pickaxe/irb.html

cb, irb_change_binding [ obj ]
    Creates and enters a new binding that has its own scope for local
variables. If obj is given, it will be used as self in the new binding.

irb [obj]
    Starts an irb subsession. If obj is given, it will be used as self.

jobs, irb_jobs
    Lists irb subsessions.

fg n, irb_fg n
    Switches into the specified irb subsession. n may be any of the
following values:

    irb subsession number
    thread id
    irb object
    self (the obj that launched a particular subsession)

kill n, irb_kill n
    Kills an irb subsession. n may be any of the values as described for
irb_fg.

7

John Joyce wrote:

well, nobody claimed black magic, just that it is interesting and fun to
play with. Sometimes people forget about the fun interesting aspects of
irb.

r-e-s-t-c-e-p (: