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POChallenge: elegantly LINQify this procedural code
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  1. POChallenge: elegantly LINQify this procedural code
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    copied!<pre><code>string[] filesOfType1 = GetFileList1(); string[] filesOfType2 = GetFileList2(); var cookieMap = new Dictionary&lt;string, CookieContainer&gt;(); Action&lt;string, Func&lt;string, KeyValuePair&lt;string, CookieContainer&gt;&gt;&gt; addToMap = (filename, pairGetter) =&gt; { KeyValuePair&lt;string, CookieContainer&gt; cookiePair; try { cookiePair = pairGetter(filename); } catch { Console.WriteLine("An error was encountered while trying to read " + file + "."); return; } if (cookieMap.ContainsKey(cookiePair.Key)) { if (cookiePair.Value.Count &gt; cookieMap[cookiePair.Key].Count) { cookieMap[cookiePair.Key] = cookiePair.Value; } } else { cookieMap.Add(cookiePair.Key, cookiePair.Value); } }; foreach (string file in filesOfType1) { addToMap(file, GetType1FileCookiePair); } foreach (string file in filesOfType2) { addToMap(file, GetType2FileCookiePair); } </code></pre> <p>Salient features that must be preserved:</p> <ul> <li>Files of type 1 are more important than files of type 2; i.e. if a file of type 1 maps to a (key, value1) combination and a file of type 2 maps to a (key, value2) combination, then we add (key, value1) to cookieMap and <em>not</em> (key, value2). <strong>Edit: as pointed out by Bevan, this is not satisfied by my original procedural code.</strong></li> <li>Secondarily, <code>CookieContainer</code>s with a higher <code>Count</code> have higher priority, i.e. if there are two (key, value) combos for the same key and both from the same filetype, we choose the one with higher <code>value.Count</code>.</li> <li>Per-case exception handling is a must; screwing up a single file-reading should just allows us to note that and continue.</li> </ul> <p>My best attempt started like this:</p> <pre><code>var cookieMap = (filesOfType1.Select(file =&gt; GetType1FileCookiePair(file)) .Concat(filesOfType2.Select(file =&gt; GetType2FileCookiePair(file)))) .GroupBy(pair =&gt; pair.Key) .Select(/* some way of selecting per the above bullets */) .ToDictionary(pair =&gt; pair.Key, pair =&gt; pair.Value); </code></pre> <p>But it's inelegant and filling in that comment block seems like a bitch. Right now I'm happy to stay procedural, but I thought that it might be a fun challenge to see if people can come up with something really clever.</p>
 

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