diff options
Diffstat (limited to 'doc/syntax')
| -rw-r--r-- | doc/syntax/control_expressions.rdoc | 26 |
1 files changed, 13 insertions, 13 deletions
diff --git a/doc/syntax/control_expressions.rdoc b/doc/syntax/control_expressions.rdoc index e91b03e72d..df3b5ced38 100644 --- a/doc/syntax/control_expressions.rdoc +++ b/doc/syntax/control_expressions.rdoc @@ -513,9 +513,9 @@ and modifier +if+ has lower precedence than <code>=</code>. == Flip-Flop -The flip-flop is a rarely seen conditional expression. It's primary use is -for processing text from ruby one-line programs used with <code>ruby -n</code> -or <code>ruby -p</code>. +The flip-flop is a slightly special conditional expression. One of its +typical uses is processing text from ruby one-line programs used with +<code>ruby -n</code> or <code>ruby -p</code>. The form of the flip-flop is an expression that indicates when the flip-flop turns on, <code>..</code> (or <code>...</code>), then an expression @@ -524,7 +524,6 @@ will continue to evaluate to +true+, and +false+ when off. Here is an example: - selected = [] 0.upto 10 do |value| @@ -533,15 +532,16 @@ Here is an example: p selected # prints [2, 3, 4, 5, 6, 7, 8] -In the above example, the on condition is <code>n==2</code>. The flip-flop -is initially off (false) for 0 and 1, but becomes on (true) for 2 and remains -on through 8. After 8 it turns off and remains off for 9 and 10. +In the above example, the `on' condition is <code>n==2</code>. The flip-flop +is initially `off' (false) for 0 and 1, but becomes `on' (true) for 2 and +remains `on' through 8. After 8 it turns off and remains `off' for 9 and 10. -The flip-flop must be used inside a conditional such as +if+, +while+, -+unless+, +until+ etc. including the modifier forms. +The flip-flop must be used inside a conditional such as <code>!</code>, +<code>? :</code>, +not+, +if+, +while+, +unless+, +until+ etc. including the +modifier forms. -When you use an inclusive range (<code>..</code>), the off condition is -evaluated when the on condition changes: +When you use an inclusive range (<code>..</code>), the `off' condition is +evaluated when the `on' condition changes: selected = [] @@ -555,7 +555,7 @@ Here, both sides of the flip-flop are evaluated so the flip-flop turns on and off only when +value+ equals 2. Since the flip-flop turned on in the iteration it returns true. -When you use an exclusive range (<code>...</code>), the off condition is +When you use an exclusive range (<code>...</code>), the `off' condition is evaluated on the following iteration: selected = [] @@ -567,5 +567,5 @@ evaluated on the following iteration: p selected # prints [2, 3, 4, 5] Here, the flip-flop turns on when +value+ equals 2, but doesn't turn off on the -same iteration. The off condition isn't evaluated until the following +same iteration. The `off' condition isn't evaluated until the following iteration and +value+ will never be two again. |