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<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D'>Regarding the aside, you can pass Float, Bignum, Complex or any
other class you choose to define to the Fixnum#+ operator so you do need an
overload with object. I seem to remember it then coerces the fixnum to
whatever the other type is and then calls + on the coerced object.<o:p></o:p></span></p>
<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D'><o:p> </o:p></span></p>
<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D'>Without looking at the code I can’t comment on the main thrust
of the mail, but shouldn’t the local variable i be a Fixnum from the word go
and therefore call the LessThan(int, int) method anyway?<o:p></o:p></span></p>
<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D'>Pete<o:p></o:p></span></p>
<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D'><o:p> </o:p></span></p>
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<p class=MsoNormal><b><span lang=EN-US style='font-size:10.0pt;font-family:
"Tahoma","sans-serif"'>From:</span></b><span lang=EN-US style='font-size:10.0pt;
font-family:"Tahoma","sans-serif"'> ironruby-core-bounces@rubyforge.org
[mailto:ironruby-core-bounces@rubyforge.org] <b>On Behalf Of </b>Wayne Kelly<br>
<b>Sent:</b> Tuesday,05 February 05, 2008 03:36<br>
<b>To:</b> ironruby-core@rubyforge.org<br>
<b>Subject:</b> [Ironruby-core] ConvertTo vs Cast<o:p></o:p></span></p>
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<p class=MsoNormal><o:p> </o:p></p>
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<p class=MsoNormal><span style='color:black'>Consider the following Ruby code:</span><o:p></o:p></p>
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<p class=MsoNormal> <o:p></o:p></p>
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<p class=MsoNormal>i = 0<o:p></o:p></p>
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<p class=MsoNormal>while (i < 1000)<o:p></o:p></p>
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<p class=MsoNormal> i = i + 1<o:p></o:p></p>
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<p class=MsoNormal>end<o:p></o:p></p>
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<p class=MsoNormal> <o:p></o:p></p>
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<p class=MsoNormal>When run using IronRuby, the (i < 1000) comparison
results in method ConvertToInt32 being invoked to convert local i into an
integer, however, the i +1 operation simply casts i to be an integer.<o:p></o:p></p>
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<p class=MsoNormal> <o:p></o:p></p>
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<p class=MsoNormal>(IronPython performs a cast in both cases to avoid the
method call to ConvertToInt32)<o:p></o:p></p>
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<p class=MsoNormal> <o:p></o:p></p>
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<p class=MsoNormal>It appears that the difference in behaviour of these two
method calls in IronRuby is due to the fact that the first argument for the
LessThan method is not overloaded:<o:p></o:p></p>
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<p><span style='color:blue'> public</span> <span style='color:blue'>static</span>
<span style='color:blue'>bool</span> LessThan(<span style='color:blue'>int</span>
self, <span style='color:blue'>int</span> other)<o:p></o:p></p>
<p><span style='color:blue'> public</span> <span style='color:blue'>static</span>
<span style='color:blue'>bool</span> LessThan(<span style='color:teal'>CodeContext</span><span
style='color:green'>/*!*/</span> context, <span style='color:blue'>int</span>
self, <span style='color:blue'>object</span> other)<span style='font-size:10.0pt'><o:p></o:p></span></p>
<p><span style='font-size:10.0pt'> <o:p></o:p></span></p>
<p>but the first argument for the Add method is overloaded:<span
style='font-size:10.0pt'><o:p></o:p></span></p>
<p><span style='color:blue'> public</span> <span style='color:blue'>static</span>
<span style='color:blue'>object</span> Add(<span style='color:blue'>int</span>
self, <span style='color:blue'>int</span> other)<span style='font-size:10.0pt'><o:p></o:p></span></p>
<p><span style='color:blue'> public</span> <span style='color:blue'>static</span>
<span style='color:blue'>double</span> Add(<span style='color:blue'>int</span>
self, <span style='color:blue'>double</span> other)<span style='font-size:10.0pt'><o:p></o:p></span></p>
<p><span style='color:blue'> public</span> <span style='color:blue'>static</span>
<span style='color:blue'>object</span> Add(<span style='color:teal'>CodeContext</span><span
style='color:green'>/*!*/</span> context, <span style='color:blue'>object</span>
self, <span style='color:blue'>object</span> other)<span style='font-size:10.0pt'><o:p></o:p></span></p>
<p><span style='font-size:10.0pt'> <o:p></o:p></span></p>
<p>Note, this only affects performance, not correctness. Eliminating the call
to ConvertToInt32 makes the program execute about 10% faster.<span
style='font-size:10.0pt'><o:p></o:p></span></p>
<p><span style='font-size:10.0pt'> <o:p></o:p></span></p>
<p>As an aside, is there really a need for an overloaded Add method with a
self of type object rather than int?<span style='font-size:10.0pt'><o:p></o:p></span></p>
<p>Ironically, making the types stronger in this way would make the
performance worse with the current implementation.<span style='font-size:
10.0pt'><o:p></o:p></span></p>
<p><span style='font-size:10.0pt'> <o:p></o:p></span></p>
<p>Or am I completely mistaken?<span style='font-size:10.0pt'><o:p></o:p></span></p>
<p><span style='font-size:10.0pt'> <o:p></o:p></span></p>
<p>Cheers, Wayne.<span style='font-size:10.0pt'><o:p></o:p></span></p>
<p><span style='font-size:10.0pt'> <o:p></o:p></span></p>
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