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Yes, everybody and his dog has hacked his .irbrc in order to use RI and complete methods. You've seen it in rubygarden and then in wirble.

But really, typing

 Object.ri "object_id"

is way too much work.

sheepman showed the way to combine method completion and RI, and here's my improvement on it: thanks to FastRI*1 being much faster than RI, you can discover where a method came from and get the corresponding documentation:

You use it like this:

>> 1.0.ri_[TAB]
1.0.ri_"%"        1.0.ri_class          1.0.ri_instance_variable_set   1.0.ri_respond_to?
1.0.ri_"*"         1.0.ri_clone          1.0.ri_instance_variables      1.0.ri_ri_
1.0.ri_"**"        1.0.ri_coerce         1.0.ri_integer?                1.0.ri_round
>> 1.0.ri_p[TAB]
1.0.ri_prec               1.0.ri_prec_i             1.0.ri_protected_methods  
1.0.ri_prec_f             1.0.ri_private_methods    1.0.ri_public_methods

For each #method, you'll get the corresponding #ri_method completion. You can also do

 >> r 'String#strip'

but now also with completion.

Finding out where the methods come from.

If you have

a = {}

with previous RI+irb hacks you might have tried

Hash.ri "inject"

Leaving the unneeded typing aside, you'd have obtained

Nothing known about Hash#inject

In other words: you'd have to know where the method comes from, that is, in which class/module it was defined. Now, that's easy for Enumerable#inject, but did you know about e.g. Precision#prec?

My irbrc hack looks for the method in all the ancestors of the receiver's class, so you don't need to know where the method you knew (maybe) nothing about (besides the name) to begin with comes from.

This is where FastRI enters the picture: the older RI can take over one second per lookup even when all your RI docs are cached and you don't hit the disk, and much longer (about 5 seconds for me) for the first one.

So

>> 1.0.ri_object_id

could take over 10 seconds with RI. It's under half a second for FastRI*2 -- and half of that time is actually spent formatting the description.