# Irb: Is it possible to automatically create a subsession on startup?

**URL:** <https://www.ruby-forum.com/t/irb-is-it-possible-to-automatically-create-a-subsession-on-startup/151982>\
**Category:** Ruby\
**Created:** [October 28, 2008, 6:20pm UTC](https://www.ruby-forum.com/t/irb-is-it-possible-to-automatically-create-a-subsession-on-startup/151982 "2008-10-28T18:20:55Z")\
**Posts on this page:** 7\
**Page:** 1

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**Author:** ![wfisk](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/w/a88e57/32.png) [@wfisk](https://www.ruby-forum.com/u/wfisk)\
**Post date:** [October 28, 2008, 6:20pm UTC](https://www.ruby-forum.com/t/irb-is-it-possible-to-automatically-create-a-subsession-on-startup/151982/1 "2008-10-28T18:20:55Z")

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In irb I can create an object and then create a new subsession with  
that object as the context.  
For example in irb I can type  
$psauto = PSAuto::Automator.new  
irb $psauto

Now I can call all the methids of $psauto without having to type the  
‘$psauto’ each time.

Is it possible to put these two lines into an irb config file so that  
I do not have to type them every time I start irb?

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<div class="post-metadata">

**Author:** ![wfisk](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/w/a88e57/32.png) [@wfisk](https://www.ruby-forum.com/u/wfisk)\
**Post date:** [October 28, 2008, 7:22pm UTC](https://www.ruby-forum.com/t/irb-is-it-possible-to-automatically-create-a-subsession-on-startup/151982/2 "2008-10-28T19:22:59Z")

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> Is it possible to put these two lines into an irb config file so that  
> I do not have to type them every time I start irb?

I believe there’s a ~/.irbrc  
-=R

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<div class="post-metadata">

**Author:** ![wfisk](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/w/a88e57/32.png) [@wfisk](https://www.ruby-forum.com/u/wfisk)\
**Post date:** [October 28, 2008, 8:36pm UTC](https://www.ruby-forum.com/t/irb-is-it-possible-to-automatically-create-a-subsession-on-startup/151982/3 "2008-10-28T20:36:08Z")

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yes I am using .irbrc, but it doesn’t work when you pur  
‘irb $psauto’ in it. At least it doesn’t work for me

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<div class="post-metadata">

**Author:** ![wfisk](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/w/a88e57/32.png) [@wfisk](https://www.ruby-forum.com/u/wfisk)\
**Post date:** [October 28, 2008, 9:04pm UTC](https://www.ruby-forum.com/t/irb-is-it-possible-to-automatically-create-a-subsession-on-startup/151982/4 "2008-10-28T21:04:55Z")

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William F. wrote:

> yes I am using .irbrc, but it doesn’t work when you pur  
> ‘irb $psauto’ in it. At least it doesn’t work for me

Try this in .irbrc:

module IRB  
def IRB.start\_session(\*args)  
unless $irb  
IRB.setup nil  
end

```
 workspace = WorkSpace.new(*args)

 if @CONF[:SCRIPT] ## normally, set by parse_opts
   $irb = Irb.new(workspace, @CONF[:SCRIPT])
 else
   $irb = Irb.new(workspace)
 end

 @CONF[:IRB_RC].call($irb.context) if @CONF[:IRB_RC]
 @CONF[:MAIN_CONTEXT] = $irb.context

 trap 'INT' do
   $irb.signal_handle
 end

 custom_configuration if defined?(IRB.custom_configuration)

 catch :IRB_EXIT do
   $irb.eval_input
 end

```

end  
end

x = Object.new  
puts “\nStarted irb shell for x”  
IRB.start\_session(x)

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<div class="post-metadata">

**Author:** ![wfisk](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/w/a88e57/32.png) [@wfisk](https://www.ruby-forum.com/u/wfisk)\
**Post date:** [October 28, 2008, 9:56pm UTC](https://www.ruby-forum.com/t/irb-is-it-possible-to-automatically-create-a-subsession-on-startup/151982/5 "2008-10-28T21:56:37Z")

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William F. wrote:

> warning: already initialized constant CantReturnToNormalMode  
> /System/Library/Frameworks/Ruby.framework/Versions/1.8/usr/lib/ruby/1.8/e2mmap.rb:152:  
> warning: already initialized constant CantChangeBinding
> 
> However, I googled “IRB.start\_session” and found some other interesting  
> post and replies (all by you I think!); and I can see other things are  
> possible.  
> I’m going to look at this again tomorrow.
> 
> Thanks
> 
> William

Sorry, cut-and-paste error ☹

Removing the

```
   IRB.setup nil

```

call should help. Here’s the code for .irbrc:

module IRB  
def IRB.start\_session(\*args)  
workspace = WorkSpace.new(\*args)

```
 if @CONF[:SCRIPT] ## normally, set by parse_opts
   $irb = Irb.new(workspace, @CONF[:SCRIPT])
 else
   $irb = Irb.new(workspace)
 end

 @CONF[:IRB_RC].call($irb.context) if @CONF[:IRB_RC]
 @CONF[:MAIN_CONTEXT] = $irb.context

 trap 'INT' do
   $irb.signal_handle
 end

 custom_configuration if defined?(IRB.custom_configuration)

 catch :IRB_EXIT do
   $irb.eval_input
 end

```

end  
end

x = Object.new  
puts “\nStarted irb shell for x”  
IRB.start\_session(x)

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<div class="post-metadata">

**Author:** ![wfisk](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/w/a88e57/32.png) [@wfisk](https://www.ruby-forum.com/u/wfisk)\
**Post date:** [October 28, 2008, 9:49pm UTC](https://www.ruby-forum.com/t/irb-is-it-possible-to-automatically-create-a-subsession-on-startup/151982/6 "2008-10-28T21:49:19Z")

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Joel,

Thanks for that. Unfortunately it doesn’t work for me.  
I get lots of errors like the following

/System/Library/Frameworks/Ruby.framework/Versions/1.8/usr/lib/ruby/1.8/e2mmap.rb:152:  
warning: already initialized constant UnrecognizedSwitch  
/System/Library/Frameworks/Ruby.framework/Versions/1.8/usr/lib/ruby/1.8/e2mmap.rb:152:  
warning: already initialized constant NotImplementedError  
/System/Library/Frameworks/Ruby.framework/Versions/1.8/usr/lib/ruby/1.8/e2mmap.rb:152:  
warning: already initialized constant CantReturnToNormalMode  
/System/Library/Frameworks/Ruby.framework/Versions/1.8/usr/lib/ruby/1.8/e2mmap.rb:152:  
warning: already initialized constant IllegalParameter  
/System/Library/Frameworks/Ruby.framework/Versions/1.8/usr/lib/ruby/1.8/e2mmap.rb:152:  
warning: already initialized constant IrbAlreadyDead  
/System/Library/Frameworks/Ruby.framework/Versions/1.8/usr/lib/ruby/1.8/e2mmap.rb:152:  
warning: already initialized constant IrbSwitchedToCurrentThread  
/System/Library/Frameworks/Ruby.framework/Versions/1.8/usr/lib/ruby/1.8/e2mmap.rb:152:  
warning: already initialized constant NoSuchJob  
/System/Library/Frameworks/Ruby.framework/Versions/1.8/usr/lib/ruby/1.8/e2mmap.rb:152:  
warning: already initialized constant CantShiftToMultiIrbMode  
/System/Library/Frameworks/Ruby.framework/Versions/1.8/usr/lib/ruby/1.8/e2mmap.rb:152:  
warning: already initialized constant CantChangeBinding

However, I googled “IRB.start\_session” and found some other interesting  
post and replies (all by you I think!); and I can see other things are  
possible.  
I’m going to look at this again tomorrow.

Thanks

William

---

<div class="post-metadata">

**Author:** ![wfisk](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/w/a88e57/32.png) [@wfisk](https://www.ruby-forum.com/u/wfisk)\
**Post date:** [October 28, 2008, 10:14pm UTC](https://www.ruby-forum.com/t/irb-is-it-possible-to-automatically-create-a-subsession-on-startup/151982/7 "2008-10-28T22:14:22Z")

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Hey Joel,

Thanks man, that works. I did start looking at the IRB code but it was  
too complicated for me.

Now time for bed.