From: George Ogata <g_ogata@...>
Date: 2006-02-21T12:38:32+09:00
Subject: Re: dirty ranges

dvandeun@vub.spam-me-not.ac.be (Dirk van Deun) writes:

> It seems that you can do destructive operations on the minimum element
> of a range, but not on the maximum element (well, you can, but it
> does not have any effect):
>
> irb(main):001:0> rng="a".."z"
> => "a".."z"
> irb(main):002:0> rng.min[0]="b"
> => "b"
> irb(main):003:0> rng.max[0]="y"
> => "y"
> irb(main):004:0> rng
> => "b".."z"

You can modify the endpoints if you reference them using #begin and
#end:

irb(main):001:0> r = 'a'..'z'
=> "a".."z"
irb(main):002:0> r.begin << '!'
=> "a!"
irb(main):003:0> r.end << '!'
=> "z!"
irb(main):004:0> r
=> "a!".."z!"

#begin and #end are direct accessors to the endpoint objects, whereas
#max is calculated, taking into account end-closedness.  It should not
be surprising, then, that #max and #end return different objects.

But I suggest not modifying range endpoints at all; Ranges themselves
are immutable, so changing their value indirectly like that is kinda
going against the grain.  And of course, if you ever modify your #end
while iterating over the range, it's nasal demons.