[英]IEnumerable<XElement>.Value() extension method available in VB.Net but not C#?
[英]Is IEnumerable different in VB.net and C#?
我正在將http://customfeedaggregator.codeplex.com/移植到c#,以使自己想到C#和WPF。
我陷入IEnumerable
一個問題。
有一個課-blogpost.vb
'Represents a single blog post
Class BlogPost
Private _title As String
Private _datePublished As DateTime
Private _url As Uri
Private _category As String
Property Title() As String
Get
Return _title
End Get
Set(ByVal value As String)
_title = value
End Set
End Property
Property DatePublished() As DateTime
Get
Return _datePublished
End Get
Set(ByVal value As DateTime)
_datePublished = value
End Set
End Property
Property Url() As Uri
Get
Return _url
End Get
Set(ByVal value As Uri)
_url = value
End Set
End Property
Property Category() As String
Get
Return _category
End Get
Set(ByVal value As String)
_category = value
End Set
End Property
End Class
以及一個共享功能,該功能可檢索供稿並將其轉換為博客文章。
Shared Function RetrieveFeeds(ByVal Address As String) As IEnumerable(Of BlogPost)
Dim doc As XDocument = XDocument.Load(Address)
Dim query = From item In doc...<item> _
Let DataPubblicazione = CDate(item.<pubDate>.Value).ToLocalTime _
Let TitoloPost = item.<title>.Value _
Let Url = item.<link>.Value _
Let Categoria = item.<category>.Value _
Order By DataPubblicazione Descending _
Select New BlogPost With _
{.DatePublished = DataPubblicazione, .Title = EscapeXml(TitoloPost), _
.Url = New Uri(Url), .Category = Categoria}
Return query
End Function
該類是一個標准,因此這不是問題。 但是RetreiveFeeds
很難。
這是我的C#版本:
public static IEnumerable<BlogPost> RetrieveFeeds(string Address)
{
XDocument doc = XDocument.Load(Address);
var query = from item in doc.Descendants("item")
let DataPubblicazione = Convert.ToDateTime(item.Attribute("pubDate").Value)
let TitoloPost = item.Attribute("title").Value
let Url = item.Attribute("link").Value
let Categoria = item.Attribute("category").Value
orderby DataPubblicazione descending
select new BlogPost {DataPubblicazione , EscapeXML(TitoloPost), Url, Categoria};
return query;
}
在顯示選擇新博客文章的部分顯示的錯誤是:
無法使用集合初始化程序初始化類型“ FeedMe.BlogPost”,因為它未實現“ System.Collections.IEnumerable”。
因此,是否需要在數據類中顯式實現IEnumerable? 還是我的C#端口代碼錯誤? VB.net和C#之間有區別嗎?
實際上,正確的語法在C#和VB.NET之間非常相似:
原始C#:
select new BlogPost {DataPubblicazione , EscapeXML(TitoloPost),
Url, Categoria};
更正的C#:
select new BlogPost {DatePublished = DataPubblicazione ,
Title = EscapeXML(TitoloPost),
Url = new Uri(Url),
Category = Categoria};
原始的VB.NET:
Select New BlogPost With _
{.DatePublished = DataPubblicazione, .Title = EscapeXml(TitoloPost), _
.Url = New Uri(Url), .Category = Categoria}
使用對象初始化程序聲明new BlogPost
,需要命名參數。
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