跨F＃/ C＃边界保留字段名 [英] Preserving Field names across the F#/C# boundary
问题描述
作为一个学习的过程，我做使用F＃和F＃的类型提供功能的5000线的CSV文件的一些数据分析。当我使用F＃中的类型提供程序生成的类型，自然是CSV文件的标题行成为该类型的字段名。
As a learning exercise, I am doing some data analysis on a 5000-line csv file using F# and F#'s type-provider functionality. When I use the type-provider-generated type in f#, naturally the header rows of the csv file become the field names of the type.
type restaurantCsv = CsvProvider<"C:\Users\Paul\Desktop\HealthDepartment\RestaurantRatings2013.csv",HasHeaders=true>
type RawInspectionData(filename : string) =
member this.allData = restaurantCsv.Load(filename)
member public this.inspectionsList = this.allData.Data.ToList()
member this.FilterByName(name : string) =
this.allData.Data
|> Seq.filter (fun x -> x.EstablishmentName.Contains(name))
另外，我打电话从单元测试C＃文件中的F＃代码（在一个库上面的代码创建）。它工作正常。但是，从FilterByName F＃的回报，字段名的信息不会被保留，当我消费IEnumberable。所以，我有代码，新的字段名称.Item1，项目2等。从元组映射：
Also, I am calling the F# code (in a library the above code creates) from a unit testing C# file. It works fine. But when I consume the IEnumberable that F# returns from FilterByName, the field name information is not preserved. So I have code which maps new field names to .Item1, Item2, etc. from the Tuple:
var inspectionsOnCafes = inspections2013.FilterByName("Cafe");
var inspections = (from row in inspectionsOnCafes
select new
{
inspectorID = row.Item3,
restaurantName = row.Item5,
inspectionDate = row.Rest.Item6
}).ToList();
我的提问有没有办法让C＃认识的字段名在F＃ - 生成类型，这样我就不必row.Item＃映射到一个易于阅读的字段名？换句话说，有没有一种方法可以让我有这样的代码：
My Question Is there a way to get C# to recognize the field names in the F#-generated type so I don't have to map row.Item# to an easy-to-read field name? In other words, is there a way I can have code like this:
inspectorID = row.InspectorID,
// etc.
请注意：我看了看的如何创建可从C＃中使用的F＃类型提供？但卡梅伦Taggert填入的问题，托马斯Petricek的回答在我看来是对类型供应商略有不同的方面。即使他们被点上，我不明白这一点，所以我还需要更多一点帮助。
Note: I looked at How do I create an F# Type Provider that can be used from C#? but Cameron Taggert's question and Tomas Petricek's answer seem to me to be on a slightly different aspect of type providers. Even if they are spot-on, I don't get it so I still need a little more help.
推荐答案
在F＃有两种不同类型的类型提供商。更常见和简单的人被擦除型供应商。 。而更复杂的问题是生成类型提供商
In F# there are two distinct kinds of type providers. The more common and simpler ones are erased type providers. And the more complicated ones are generative type providers.
的区别是C＃非常重要，因为：
The distinction is very important for C#, because:
-
这是擦除型供应商只是编译器法宝。这是一种方式，以确保很好形成你的代码，你是正确使用垫层API。但是，这是编译时只和无类型生成。代替垫层类型用作内部表示。这种类型的提供程序是不是很方便从C＃中使用，因为在C＃中，您只能得到垫层类型。
An erased type provider is just compiler magic. It is a way to make sure your code is well-formed, that you are using the underlaying API correctly. But this is compile-time only and no types are generated. Instead the underlaying type is used as an internal representation. This kind of type provider is not very convenient to use from C#, because in C# you only get the underlaying types.
一个生成类型的提供是一个真正的代码产生步骤，在编译时。在这种情况下的类型生成并因此实际上在装配存在，可以从C＃中使用。
A generative type provider is a true code generation step at compile-time. In this case types are generated and therefore actually exist in the assembly and can be used from C#.
你所描述的是什么人会从被擦除类型供应商的期望问题。而在垫层类型仅仅是一个元组，但没有很好的型象类或生成一个记录。而且你不能在C＃中使用F＃的名字，除非型供应商都以不同的方式写成生成型供应商。
The problem you are describing would be exactly what one would expect from an erased type provider. Whereas the underlaying type is just a tuple, but no nice type like a class or a record is generated. And you cannot use the F# names in C#, unless the type provider were to be written differently as a generative type provider.
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