///& lt; Summary> 
///according to the specified attribute name 
 sorting sequence///& lt;/summary> 
///& lt; Typeparam name="T" & gt; The type of the elements in the source & lt;/typeparam> 
///& lt; Param name="source" & gt; To sort the values of the sequence & lt;/param> 
///& lt; Param name="property" & gt; The attribute name & lt;/param> 
///& lt; Param name="item first-just & gt;" Whether descending & lt;/param> 
///& lt; Returns>  
Public static IEnumerable OrderBy (this IEnumerable The source, the string property, bool item first-just) where T: class 
{
ParameterExpression param=Expression. The Parameter (typeof (T), "c"); 
PropertyInfo PI=typeof (T). GetProperty (property); 
MemberExpression selector=Expression. MakeMemberAccess (param, PI); 
LambdaExpression le=Expression. Lambda (selector, param); 
String methodName=(item first-just)? "OrderByDescending" : the "OrderBy"; 
MethodCallExpression resultExp=Expression. The Call (typeof (Queryable), methodName, new Type [] {typeof (T), PI, PropertyType}, source, Expression, le); 
Return to the source. The Provider. CreateQuery (resultExp); 
} 

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