[Ruby Forum] irb feature suggestion

[Alexey Verkhovsky]

Cross-posted from Ruby Forum:
http://www.ruby-forum.org/bb/viewtopic.php?t=62

----

How do you get the value of the last expression entered in irb?

SML/NJ puts it in the variable 'it', Python uses '_', I think.
So you can do something like this:
Code:

6*9 => it = 54
it - 12

=> it = 42

Can you do this in Irb? It's very useful for evaluating expressions
interactively, without cluttering up your symbol table (e.g. when
evaluating something piece-by-piece to see how it's working.)

For example, I just did
Code:
YAML::load(<<END)
# ... some YAML here ...
END
and got the right result, then realised I had no way of using it.

 

[Mark Hubbart]

Cross-posted from Ruby Forum:
http://www.ruby-forum.org/bb/viewtopic.php?t=62

----

How do you get the value of the last expression entered in irb?

SML/NJ puts it in the variable 'it', Python uses '_', I think.
So you can do something like this:
Code:
=> it = 42

Can you do this in Irb? It's very useful for evaluating expressions
interactively, without cluttering up your symbol table (e.g. when
evaluating something piece-by-piece to see how it's working.)

For example, I just did
Code:
YAML::load(<<END)
# ... some YAML here ...
END
and got the right result, then realised I had no way of using it.

I distinctly remembered this one from a few months back...

In ruby-talk:102888, Nobu Nakada said:

EVAL_HISTORY enables _.

$ grep HISTORY ~/.irbrc
IRB.conf[:EVAL_HISTORY] = 1000
IRB.conf[:SAVE_HISTORY] = 100

$ irb
irb(main):001:0> 2+2
=> 4
irb(main):002:0> _
=> 4
irb(main):003:0>

So, just add those lines to your ~/.irbrc, and that's it.

HTH,
Mark

 

[Dave Thomas]

How do you get the value of the last expression entered in irb?

dave[ruby/lib 14:26:14] irb
irb(main):001:0> 1 + 2
=> 3
irb(main):002:0> conf.last_value
=> 3



Cheers

Dave