IEnumerable在VB.net和C＃中是否有所不同？

Question

I am porting http://customfeedaggregator.codeplex.com/ to c#, to make myself think in C# and WPF.

I am stuck on an issue in IEnumerable .

There's a class - 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

and a shared function that retrieves feeds and converts them to blogposts.

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

The class is a standard, so that wasn't an issue. But the RetreiveFeeds is being difficult.

Here's my C# version:

 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;
    }

The error shown at the part where it says Select New Blogpost is:

Cannot initialize type 'FeedMe.BlogPost' with a collection initializer because it does not implement 'System.Collections.IEnumerable'.

So, do I need to explicitly implement IEnumerable in my dataclass? or is my C# Port code wrong? Is this a difference between VB.net and C#?

Answer 1

Actually the correct syntax is very similar between C# and VB.NET:

Original C#:

select new BlogPost {DataPubblicazione ,  EscapeXML(TitoloPost),  
                     Url, Categoria};

Corrected C#:

select new BlogPost {DatePublished = DataPubblicazione , 
                     Title = EscapeXML(TitoloPost),  
                     Url = new Uri(Url), 
                     Category = Categoria};

Original VB.NET:

Select New BlogPost With _
    {.DatePublished = DataPubblicazione, .Title = EscapeXml(TitoloPost), _
     .Url = New Uri(Url), .Category = Categoria}

When declaring a new BlogPost with an object initializer you need to name the parameters.