[英]C# Best way to share logic and re-use code
給定函數返回KPI值,首先檢查其緩存,然后執行其邏輯,緩存結果並返回值,處理失敗條件。
我怎樣才能最好地重用緩存,錯誤處理邏輯。 我本質上想要創建的是一個函數,只需執行必要的邏輯,抽象出鍋爐板代碼,並在多個類似函數中重復使用。
public static int CurrentEmployees()
{
if (HttpRuntime.Cache["CurrentEmployees"] == null)
{
try
{
int CurrentEmployees = Employee.Load().Count(x => x.DateFinished == null && !x.Contractor && x.DateStarted < DateTime.Now);
HttpRuntime.Cache.Insert("CurrentEmployees", CurrentEmployees, null, DateTime.Now.AddMinutes(20), new TimeSpan(0, 10, 0));
return CurrentEmployees;
}
catch(Exception e)
{
//TODO: Report this
return -1;
}
}
else
return (int)HttpRuntime.Cache["CurrentEmployees"];
}
由於樣板代碼包含在邏輯中,因此我很難將它們簡單地推送到其他函數調用中。
以下是如何創建一個通用方法來緩存您想要的任何內容並重用此邏輯。
public static T Cache<T>(string key, Func<T> loadFunction, Func<T> errorHandler)
{
if (HttpRuntime.Cache[key] == null)
{
try
{
T value = loadFunction();
HttpRuntime.Cache.Insert(key, value , null, DateTime.Now.AddMinutes(20), new TimeSpan(0, 10, 0));
return value;
}
catch(Exception e)
{
//TODO: Report this
return errorHandler();
}
}
else
return (T)HttpRuntime.Cache[key];
}
用法:
public static int CurrentEmployees()
{
return Cache<int>("CurrentEmployees",
() => Employee.Load().Count(x => x.DateFinished == null && !x.Contractor && x.DateStarted < DateTime.Now),
() => -1);
}
同意來自@DLeh的回答,但我會這樣寫:
public static class HelperFunctions
{
public static Func<T> Cache<T>(this Func<T> inner, string cacheName)
{
return () =>
{
if (HttpRuntime.Cache[cacheName] == null)
{
var result = inner();
HttpRuntime.Cache.Insert(cacheName, inner(), null, DateTime.Now.AddMinutes(20), new TimeSpan(0, 10, 0));
return result;
}
return (T)HttpRuntime.Cache[cacheName];
};
}
public static Func<T> OnError<T>(this Func<T> inner, Func<Exception, T> onError)
{
return () =>
{
try
{
return inner();
}
catch (Exception e)
{
return onError(e);
}
};
}
}
用法:
public static class Employees
{
public static int CurrentEmployees()
{
return (new Func<int>(() => Employee.Load().Count(x => x.DateFinished == null && !x.Contractor && x.DateStarted < DateTime.Now)))
.Cache("CurrentEmployees")
.OnError(e => -1)
();//TODO: log?
}
}
這樣我們就將緩存邏輯與錯誤處理(遵循單一責任原則)分開,並且能夠分別重用/組合每個。 所以當你添加這樣的另一個函數時,你不必更改緩存功能。
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