有一个LINQ方法单一项目添加到IEnumerable＆LT; T＆GT;？ [英] Is there a Linq method to add a single item to an IEnumerable<T>?

问题描述

基本上我试图做这样的事情：

Basically I am trying to do something like this:

image.Layers

它返回一个IEnumerable为除父层全层，但在某些情况下，我只想做：

which returns an IEnumerable for all layers except the Parent layer, but in some cases, I just want to do:

image.Layers.With(image.ParentLayer);

，因为它仅用于少数地方相比，通常使用的是由 image.Layers 纳100S。这就是为什么我不想再拍属性也返回了父层。

because it's only used in a few places compared to the 100s of the usual usage which is satisfied by image.Layers. That's why I don't want to make another property that also returns the Parent layer.

推荐答案

一种方法是创建一个单独序列出的项目（如数组），然后 Concat的它拖到原来的：

One way would be to create a singleton-sequence out of the item (such as an array), and then Concat it onto the original:

image.Layers.Concat(new[] { image.ParentLayer } )

如果你这样做真的的时候，考虑写一个追加（或类似）扩展法，如一个<一个href="http://stackoverflow.com/questions/3645644/whats-your-favorite-linq-to-objects-operator-which-is-not-built-in/3645715#3645715">listed这里，这将让你做：

If you're doing this really often, consider writing an Append (or similar) extension-method, such as the one listed here, which would let you do:

image.Layers.Append(image.ParentLayer)

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