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Here's a slightly longer example, showing a genuine application---a
``pig Latin'' generator.
Type in the phrase such as ``Ruby rules,''
and the ``Pig It'' button will instantly translate it into pig Latin.
require 'tk'
class PigBox
def pig(word)
leadingCap = word =~ /^A-Z/
word.downcase!
res = case word
when /^aeiouy/
word+"way"
when /^([^aeiouy]+)(.*)/
$2+$1+"ay"
else
word
end
leadingCap ? res.capitalize : res
end
def showPig
@text.value = @text.value.split.collect{|w| pig(w)}.join(" ")
end
def initialize
ph = { 'padx' => 10, 'pady' => 10 } # common options
p = proc {showPig}
@text = TkVariable.new
root = TkRoot.new { title "Pig" }
top = TkFrame.new(root)
TkLabel.new(top) {text 'Enter Text:' ; pack(ph) }
@entry = TkEntry.new(top, 'textvariable' => @text)
@entry.pack(ph)
TkButton.new(top) {text 'Pig It'; command p; pack ph}
TkButton.new(top) {text 'Exit'; command {proc exit}; pack ph}
top.pack('fill'=>'both', 'side' =>'top')
end
end
PigBox.new
Tk.mainloop
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Sidebar: Geometry Management
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In the example code in this chapter,
you'll see references to the
widget method pack. That's a very important call, as it
turns out---leave it off and you'll never see the widget. pack
is a command that tells the geometry manager to place the widget
according to constraints that we specify. Geometry managers
recognize three commands:
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Command
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Placement Specification
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pack
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Flexible, constraint-based placement |
place
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Absolute position |
grid
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Tabular (row/column) position |
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As pack is the most commonly used command, we'll use it
in our examples.
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