From: Ben Brightwell <neogia4@...>
Date: 2008-07-29T13:55:08+09:00
Subject: Re: and and or in case

Pe単a,

The way I see it (and also the way I practice it today) is to always 
always always use "&&" or "||" over "and" or "or", respectively.

The words "and" and "or" are lower in the order of operators than the 
symbols "&&" and "||". This is intentional for beginner programmers to 
be able to "read" the code rather than work out the logic of the code. 
Take this for an example:

When using the symbolic operator "||", ruby sees what you write like 
this:

case
(when (1==1 || 2==2))  # good "when" keyword and good expression to 
satisfy it
  puts "ok"
end

This is good syntax, and gives the "when" keyword what it is looking 
for, an expression.

When using the word operator "or", ruby sees it like this:

case
(when 1==1) or (2==2)  # good "when" keyword, expression, but then 
additional "or" keyword
  puts "ok"
end

While this reads ok in language, it doesn't quite work for ruby. Because 
the word "or" gets tried lower in the order of operators, it concludes 
the "when" keyword with a satisfactory expression, 1==1. Now the "case" 
keyword is satisfied with a proper "when" keyword. Ruby throws up its 
red flag when it sees something else past the good expression. To ruby 
this would be likewise -wrong- to do:

case
(when (1==1 || 2==2)) or (3==3)
  puts "ok"
end

It's all good until the additional "or" keyword.

Just remember that ruby sees the "&&"/"||" and "and"/"or" as completely 
different operators.
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