本文轉載：http://joe-bq-wang.iteye.com/blog/1872756
里面有動態Linq to xml的寫法。
There is a expando object which allow you add/remove properties at runtime, DynamicObject provides ou with more capability and it is better used in places where a wrapper excels a raw XML file or script object syntax.?
First, we will intoduce the ?DynamicObject, as stated in the References Section on "DynamicObject Class",which defines some methods such as TryGetMember, TrySetMember, TryInvokeMembers which acts as a proxy to the real value contained in the DynamicObject derived classes. Also, DynamicObject has special support from the DLR (Dynamic Language Runtime) which means it has some special translation when you use DynamicObject with "dynamic" keyword.?
?
First, we will see a example object with DynamicObject which has the ability to let you query/set values in case-insensitive fashion, which the real data is backed by a Dictionary.?
?
?
C#代碼??
using?System.Collections.Generic;?? using?System.Dynamic;?? ?? namespace?DynamicObjectDemo?? {?? ????class?DynamicDictionary?:?DynamicObject?? ????{?? ????????private?Dictionary<string,?object>?dictionary?=?new?Dictionary<string,?object>();?? ?? ?? ????????public?int?Count?? ????????{?? ????????????get?{?return?dictionary.Count;?}?? ????????}?? ?? ?? ????????public?override?bool?TryGetMember(GetMemberBinder?binder,?out?object?result)?? ????????{?? ?? ????????????string?name?=?binder.Name.ToLower();?? ????????????return?dictionary.TryGetValue(name,?out?result);?? ????????}?? ?? ????????public?override?bool?TrySetMember(SetMemberBinder?binder,?object?value)?? ????????{?? ????????????dictionary[binder.Name.ToLower()]?=?value;?? ?? ????????????return?true;?? ????????}?? ????}?? }?? ?
?
and here is a test program to show you how to use the DynamicDictionary class.?
?
?
C#代碼??
namespace?DynamicObjectDemo?? {?? ???? ???? ???? ???? ???? ???? ???? ???? ????class?Program?? ????{?? ????????static?void?Main(string[]?args)?? ????????{?? ?? ???????????? ?? ????????????dynamic?person?=?new?DynamicDictionary();?? ?? ?? ???????????? ????????????person.FirstName?=?"Ellen";?? ????????????person.LastName?=?"Adams";?? ?? ???????????? ???????????? ????????????Console.WriteLine(person.FirstName?+?"?"?+?person.lastname);? ?? ????????????Console.WriteLine("NUmber?of?dynamic?properties"?+?person.Count);?? ?? ?? ????????????try?? ????????????{?? ???????????????? ???????????????? ???????????????? ????????????????Console.WriteLine(person.address);?? ????????????}?? ????????????catch?(RuntimeBinderException?ex)?? ????????????{?? ????????????????Debug.WriteLine("caught?exception?calling?person.address:?{0}",?ex.ToString());?? ????????????}?? ????????????catch?(Exception?ex)?? ????????????{?? ????????????????Debug.WriteLine("Some?unknown?exception?:?{0}",?ex.ToString());?? ????????????}?? ????????}?? ????}?? }?? ?
?
With DynamicObject, you can do even more, suppose that we have an XElement and we know we can create an XElement with some syntax as below.?
?
C#代碼??
XElement?contactXML?=?? ????new?XElement("Contact",?? ????new?XElement("Name",?"Patrick?Hines"),?? ????new?XElement("Phone",?"206-555-0144"),?? ????new?XElement("Address",?? ????????new?XElement("Street1",?"123?Main?St"),?? ????????new?XElement("City",?"Mercer?Island"),?? ????????new?XElement("State",?"WA"),?? ????????new?XElement("Postal",?"68042")?? ????)?? );?? ?
?
however, we can make it even simpler. what we have in mind is something like this:?
?
Haskell代碼??
dynamic?contact?=?new?DynamicXMLNode("Contacts");?? contact.Name?=?"Patrick?Hines";?? contact.Phone?=?"206-555-0144";?? contact.Address?=?new?DynamicXMLNode();?? contact.Address.Street?=?"123?Main?St";?? contact.Address.City?=?"Mercer?Island";?? contact.Address.State?=?"WA";?? contact.Address.Postal?=?"68402";?? ?
?
we might need to write Dyanmic Extended class ?with the following override.s?
?
TryGetMember : the?Contact.Address.Street part in the?Contact.Address.Street statement (the part to get some member back)?
TrySetMember:?contact.Name = "Patrick Hines";
TryConvert:?contact.Name = "Patrick Hines"; (Expected value type is String, but returned type is a DynamicXMLNode)
TryInvokeMember: we have hide the XElement , this enables us to the hidden methods supported by the Xlement
?
here is the full code of the implementation of DynamicXMLNode.
?
C#代碼??
using?System;?? using?System.Dynamic;?? using?System.Reflection;?? using?System.Xml.Linq;?? ?? namespace?DynamicObjectDemo?? {?? ???? ???? ???? ???? ???? ???? ???? ???? ???? ????public?class?DynamicXMLNode?:?DynamicObject?? ????{?? ????????XElement?node;?? ?? ????????public?DynamicXMLNode(XElement?node)?? ????????{?? ????????????this.node?=?node;?? ????????}?? ?? ????????public?DynamicXMLNode()?? ????????{?? ?????????????? ????????}?? ?? ????????public?DynamicXMLNode(string?name)?? ????????{?? ????????????node?=new?XElement(name);?? ????????}?? ?? ?? ????????public?override?bool?TryGetMember(GetMemberBinder?binder,?out?object?result)?? ????????{?? ????????????XElement?getNode?=?node.Element(binder.Name);?? ????????????if?(getNode?!=?null)?? ????????????{?? ????????????????result?=?new?DynamicXMLNode(getNode);?? ????????????????return?true;?? ????????????}?? ????????????else?? ????????????{?? ????????????????result?=?null;?? ????????????????return?false;?? ????????????}?? ????????}?? ?? ????????public?override?bool?TrySetMember(SetMemberBinder?binder,?object?value)?? ????????{?? ????????????XElement?setNode?=?node.Element(binder.Name);?? ????????????if?(setNode?!=?null)?? ????????????{?? ????????????????setNode.SetValue(binder.Name);?? ????????????}?? ????????????else?? ????????????{?? ????????????????if?(value.GetType()?==?typeof?(DynamicXMLNode))?? ????????????????{?? ????????????????????node.Add(new?XElement(binder.Name));?? ????????????????}?? ????????????????else?? ????????????????{?? ????????????????????node.Add(new?XElement(binder.Name,?value));?? ????????????????}?? ????????????}?? ????????????return?true;?? ????????}?? ?? ???????? ???????? ???????? ????????public?override?bool?TryConvert(ConvertBinder?binder,?out?object?result)?? ????????{?? ????????????if?(binder.Type?==?typeof(string))?? ????????????{?? ????????????????result?=?node.Value;?? ????????????????return?true;?? ????????????}?? ????????????else?? ????????????{?? ????????????????result?=?null;?? ????????????????return?false;?? ????????????}?? ????????}?? ?? ???????? ???????? ???????? ????????public?override?bool?TryInvokeMember(InvokeMemberBinder?binder,?object[]?args,?out?object?result)?? ????????{?? ????????????Type?xmlType?=?typeof(XElement);?? ????????????try?? ????????????{?? ????????????????result?=?xmlType.InvokeMember(binder.Name,?? ??????????????????????????????????????????????BindingFlags.InvokeMethod?|?BindingFlags.Public?|?BindingFlags.Instance,?? ??????????????????????????????????????????????null,?? ??????????????????????????????????????????????node,?? ??????????????????????????????????????????????args);?? ????????????????return?true;?? ????????????}?? ????????????catch?? ????????????{?? ????????????????result?=?null;?? ????????????????return?false;?? ????????????}?? ????????}?? ????}?? }?? ?
to give an impression on the capability that the DynamixXMLNode has empowered us, let 'see the test code below.?
C#代碼??
public?class?DynamicXMLNodeMain?? {?? ????public?static?void?DynamicXMLNodeCreateReturnValidDynamixXMLNode()?? ????{?? ????????dynamic?contact?=?CreateDynamicXMLNode();?? ????????if?(contact?!=?null)?? ????????{?? ????????????Console.WriteLine("Created?DynamicXMLNode?");?? ????????}?? ????????else?? ????????{?? ????????????Console.WriteLine("Failed?to?create?DynamicXMLNode");?? ????????}?? ????}?? ?? ????public??static?void?DynamicXMLNodeConvertToStringReturnXElementValue()?? ????{?? ????????dynamic?contact?=?CreateDynamicXMLNode();?? ????????string?state?=?contact.Address.State;?? ????????Console.WriteLine("State?is?{0}",?state);?? ????}?? ?? ????public?static?void?DynamicXMLNodeTryInvokeMemberCallXElementMethods()?? ????{?? ????????dynamic?contact?=?CreateDynamicXMLNode();?? ????????contact.Address.Postal.SetValue("newPostValue");?? ????????string?newPostal?=?contact.Address.Postal;?? ????????if?(newPostal?==?"newPostValue")?? ????????{?? ????????????Console.WriteLine("Set?new?Post?value");?? ????????}?? ????????else?? ????????{?? ????????????Console.WriteLine("Failed?to?set?new?postal?value");?? ????????}?? ????}?? ?? ????public?static?DynamicXMLNode?CreateDynamicXMLNode()?? ????{?? ????????dynamic?contact?=?new?DynamicXMLNode("Contacts");?? ????????contact.Name?=?"Patrick?Hines";?? ????????contact.Phone?=?"206-555-0144";?? ????????contact.Address?=?new?DynamicXMLNode();?? ????????contact.Address.Street?=?"123?Main?St.";?? ????????contact.Address.City?=?"Mercer?Island";?? ????????contact.Address.State?=?"NA";?? ????????contact.Address.Postal?=?"68402";?? ????????return?contact;?? ????}?? }?? ?
and this is the Main method which invoke them..?
?
C#代碼??
static?void?Main(string[]?args)?? {?? ???? ????DynamicXMLNodeMain.DynamicXMLNodeCreateReturnValidDynamixXMLNode();?? ????DynamicXMLNodeMain.DynamicXMLNodeConvertToStringReturnXElementValue();?? ????DynamicXMLNodeMain.DynamicXMLNodeTryInvokeMemberCallXElementMethods();?? ?? }?? ?
總結
以上是生活随笔 為你收集整理的C# - DynamicObject with Dynamic 的全部內容，希望文章能夠幫你解決所遇到的問題。
如果覺得生活随笔 網站內容還不錯，歡迎將生活随笔 推薦給好友。
