From: matz@... (Yukihiro Matsumoto)
Date: 2000-10-31T08:05:39+09:00
Subject: [ruby-talk:5956] Re: Hash.new {block} / Hash#default_proc{,_set}

Hi,

In message "[ruby-talk:5947] Hash.new {block} / Hash#default_proc{,_set}"
    on 00/10/31, "Brian F. Feldman" <green@FreeBSD.org> writes:

|I've done very little testing, but I think I've successfully implemented the 
|ability for a Hash to provide a default procedure rather than variable.
|
|The only reasonable way I could think of doing this required on-the-fly 
|creation of a hash entry when a lookup fails -- otherwise, this feature is 
|nearly useless (does not make anything easier).
|
|Here's the diff, my 3rd time modifying Ruby code itself.  Comments?

Three points:

  * currently each internal structure sizes are made strictly less
    than 5 pointer size for space efficiency.

  * your on-the-fly entry creation idea sound reasonable; but I think
    we need to discuss it before merging it.

  * we need to inspect cost/benefit between this patch and Hash#fetch
    which already takes a block to give a value for non existing
    entry.

Thank you anyway.

							matz.