剃刀没有编译使用块

Question

我们为HtmlHelper添加了两个扩展程序：Content和Block。 Content允许消费者使用剃刀代码创建HtmlStrings。 Block尝试允许用户使用标题和内容部分创建html块。我试图理解为什么razorContent参数不能在using块内编译。我想保留使用块的使用，因为我觉得它看起来很干净。有没有办法在不将Block上的第二个参数更改为HtmlString的情况下进行编译？

剃刀：

@* uses of Html.Content compiles as expected *@
@Html.Content(@<span>foo</span>)
@{
    IHtmlString htmlString = Html.Content(@<span>bar</span>);
}
@htmlString


@* "@<span>header</span>" does not compile
 *
 * expected markup: 
 * <div class="header">
 *     <span>header</span>
 * </div>
 * <div class="content>
 *     <span>content</span>
 * </div>
 *@
@using (Html.Block(@<span>header</span>))
{
    <span>content</span>
}

扩展：

public static class HtmlHelperExtensions
{
    public static IHtmlString Content(this HtmlHelper htmlHelper, Func<object, HelperResult> razorContent)
    {
        var content = razorContent(null);
        return content;
    }

    public static IDisposable Block(this HtmlHelper htmlHelper, Func<object, HelperResult> razorContent)
    {
        var content = razorContent(null);
        return new MyHtmlBlock(htmlHelper, content);
    }
}

MyHtmlBlock：

public class MyHtmlBlock : IDisposable
{
    private readonly TextWriter _writer;
    private readonly TagBuilder _contentTag;

    public MyHtmlBlock(HtmlHelper htmlHelper, IHtmlString header)
    {
        this._writer = htmlHelper.ViewContext.Writer;

        var headerTag = new TagBuilder("div");
        headerTag.AddCssClass("header");
        headerTag.InnerHtml = header.ToHtmlString();

        this._contentTag = new TagBuilder("div");
        this._contentTag.AddCssClass("content");

        this._writer.Write(headerTag);
        this._writer.Write(this._contentTag.ToString(TagRenderMode.StartTag));
    }
    public void Dispose()
    {
        this._writer.Write(this._contentTag.ToString(TagRenderMode.EndTag));
    }
}