Ruby style guide

Hm. Use one letter variable names for scoped variables? Excerpt from lines 92-112:<p>"* The length of an identifier determines its scope. Use one-letter variables for short block/method parameters, according to this scheme:<p><pre><code> a,b,c: any object d: directory names e: elements of an Enumerable ex: rescued exceptions f: files and file names i,j: indexes k: the key part of a hash entry m: methods o: any object r: return values of short methods s: strings v: any value v: the value part of a hash entry x,y,z: numbers And in general, the first letter of the class name if all objects are of that type."</code></pre>

<i>Do not program defensively. (See <a href="http://www.erlang.se/doc/programming_rules.shtml#HDR11." rel="nofollow">http://www.erlang.se/doc/programming_rules.shtml#HDR11.</a>) </i><p>I cross-referenced to the Erlang documentation, and they provided no other real justification for this rule, other than to say that the burden lies on the caller. Is there a history behind this convention? Is there a considerable benefit, other than more stream-lined code, to coding this way?

I'm not quite sure why this style guide is more noteworthy than all the other ruby style guides out there.. e.g.:<p><a href="http://www.caliban.org/ruby/rubyguide.shtml" rel="nofollow">http://www.caliban.org/ruby/rubyguide.shtml</a><p>and<p><a href="http://www.pathf.com/blogs/2008/10/elements-of-ruby-style/" rel="nofollow">http://www.pathf.com/blogs/2008/10/elements-of-ruby-style/</a>

I really hate other people's style-guides. Most of it is common-sense, but there's always some aspect or another that <i>really</i> grates against my preferences, e.g. "Keep lines fewer than 80 characters" is a pet hate; when did we return to Green-screen terminals?? My current company enforces this, and it often creates worse multi-line dischord cf. adding an extra 10 to 20 char's to the current line.<p>And "Read other style guides and apply the parts that don't dissent with this list" is a little too arrogant for <i>any</i> coder in the entire world -- perhaps should be "Replace any parts of this list that don't conform to your style".

This is the second time in the past few days I've been told to use two spaces instead of tabs. Can anyone provide any insight as to what difference this makes?