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copied!<p>The way you have it now, You have two write NxN <code>if</code> statements for each category that has N units.</p> <pre><code>if from_spinner is Degree if to_spinner is Degree return input if to_spinner is Radian return input * 0.0174532925199 if to_spinner is Gradian return input * 1.11111111111 if from_spinner is Radian if to_spinner is Degree return input * 57.2957795131 if to_spinner is Radian return input if to_spinner is Gradian return input * 63.6619772368 if from_spinner is Gradian if to_spinner is Degree return input * 0.9 if to_spinner is Radian return input * 0.0157079632679 if to_spinner is Gradian return input </code></pre> <p>Instead, choose a unit that will act as an intermediary between the input and the output. Then you need N <code>if</code> statements to convert from input to intermediary, and N <code>if</code> statements to convert from intermediary to output, for a total of 2N.</p> <pre><code>//we will use degrees as the intermediary unit intermediary = null //caluclate intermediary if from_spinner is Degree intermediary = input if from_spinner is Radian intermediary = input * 57.2957795131 if from_spinner is Gradian intermediary = input * 0.9 //calculate final if to_spinner is Degree return intermediary if to_spinner is Radian return intermediary / 57.2957795131 if to_spinner is Gradian return intermediary / 0.9 </code></pre> <p>It doesn't seem like it's much more efficient when you have only three units, but for larger values of N, it saves you a lot of effort. For instance, compare this 105 line doubly nested method to its 29 line equivalent that uses intermediary values:</p> <pre><code>if from_spinner is Millimeter if to_spinner is Millimeter return input if to_spinner is Centimeter return input * 0.1 if to_spinner is Meter return input * 0.001 if to_spinner is Kilometer return input * 1e-06 if to_spinner is Inch return input * 0.0393700787402 if to_spinner is Foot return input * 0.00328083989501 if to_spinner is Mile return input * 6.2137273665e-07 if from_spinner is Centimeter if to_spinner is Millimeter return input * 10.0 if to_spinner is Centimeter return input if to_spinner is Meter return input * 0.01 if to_spinner is Kilometer return input * 1e-05 if to_spinner is Inch return input * 0.393700787402 if to_spinner is Foot return input * 0.0328083989501 if to_spinner is Mile return input * 6.2137273665e-06 if from_spinner is Meter if to_spinner is Millimeter return input * 1000.0 if to_spinner is Centimeter return input * 100.0 if to_spinner is Meter return input if to_spinner is Kilometer return input * 0.001 if to_spinner is Inch return input * 39.3700787402 if to_spinner is Foot return input * 3.28083989501 if to_spinner is Mile return input * 0.00062137273665 if from_spinner is Kilometer if to_spinner is Millimeter return input * 1000000.0 if to_spinner is Centimeter return input * 100000.0 if to_spinner is Meter return input * 1000.0 if to_spinner is Kilometer return input if to_spinner is Inch return input * 39370.0787402 if to_spinner is Foot return input * 3280.83989501 if to_spinner is Mile return input * 0.62137273665 if from_spinner is Inch if to_spinner is Millimeter return input * 25.4 if to_spinner is Centimeter return input * 2.54 if to_spinner is Meter return input * 0.0254 if to_spinner is Kilometer return input * 2.54e-05 if to_spinner is Inch return input if to_spinner is Foot return input * 0.0833333333333 if to_spinner is Mile return input * 1.57828675109e-05 if from_spinner is Foot if to_spinner is Millimeter return input * 304.8 if to_spinner is Centimeter return input * 30.48 if to_spinner is Meter return input * 0.3048 if to_spinner is Kilometer return input * 0.0003048 if to_spinner is Inch return input * 12.0 if to_spinner is Foot return input if to_spinner is Mile return input * 0.000189394410131 if from_spinner is Mile if to_spinner is Millimeter return input * 1609340.0 if to_spinner is Centimeter return input * 160934.0 if to_spinner is Meter return input * 1609.34 if to_spinner is Kilometer return input * 1.60934 if to_spinner is Inch return input * 63359.8425197 if to_spinner is Foot return input * 5279.98687664 if to_spinner is Mile return input </code></pre> <p>.</p> <pre><code>intermediary = null if from_spinner is Millimeter intermediary = input * 0.001 if from_spinner is Centimeter intermediary = input * 0.01 if from_spinner is Meter intermediary = input * 1.0 if from_spinner is Kilometer intermediary = input * 1000.0 if from_spinner is Inch intermediary = input * 0.0254 if from_spinner is Foot intermediary = input * 0.3048 if from_spinner is Mile intermediary = input * 1609.34 if to_spinner is Millimeter return intermediary / 0.001 if to_spinner is Centimeter return intermediary / 0.01 if to_spinner is Meter return intermediary / 1.0 if to_spinner is Kilometer return intermediary / 1000.0 if to_spinner is Inch return intermediary / 0.0254 if to_spinner is Foot return intermediary / 0.3048 if to_spinner is Mile return intermediary / 1609.34 </code></pre>

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