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Created May 15, 2014 08:23
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重複処理 IEnumerableをそのまま使い回さない - Possible multiple enumeration of IEnumerable
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IEnumerableをそのまま使うと、使う度に毎回変換される。遅延実行。 http://confluence.jetbrains.com/display/ReSharper/Possible+multiple+enumeration+of+IEnumerable

Assuming that GetNames() returns an IEnumerable, we are, effectively, doing extra work by enumerating this collection twice in the two foreach statements. If GetNames() results in a database query, you end up doing that query twice, while both times getting the same data.

ということで、特に複数回使う場合など適宜ToList()やToArray()しておく。

参考：LINQ クエリの概要 (C#) http://msdn.microsoft.com/ja-jp/library/bb397906.aspx

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