如何在C＃中将谓词传递给函数？

Question

我有：

 public void InitializeStatusList(DropDownList list)
    {
       var dictionaryEntries = GetEntriesFromDatabase();
       list.DataSource = dictionaryEntries.Where(entry => entry is EntryStatus1 || entry is EntryStatus2);
       list.DataBind();           
    }

我有很多这样的功能。我想用dictionaryEntries作为谓词传递的查询条件编写公共函数。

例如：

public void InitializeStatusList(DropDownList list)
{
    CommonInitializeStatusList(DropDownList list, entry => entry is EntryStatus1 || entry is EntryStatus2);
}

public void CommonInitializeStatusList(DropDownList list, ??????????????? predicate)
{                       
    var dictionaryEntries = GetEntriesFromDatabase();
    list.DataSource = dictionaryEntries.Where(predicate);
    list.DataBind();        
}

什么代表???????????????

提前致谢

Answer 1

Func<Entry, bool> predicate应该有效，其中Entry是entry变量的类型。

Answer 2

你可以这样做：

public void InitializeStatusList(DropDownList list)
{    
    Func<Entry,bool> predicate=entry=>entry is EntryStatus1 || entry is EntryStatus2;
    CommonInitializeStatusList(list, predicate);
}

public void CommonInitializeStatusList(DropDownList list, Func<Entry,bool> predicate)
{                                 
    var dictionaryEntries = GetEntriesFromDatabase();    
    list.DataSource = dictionaryEntries.Where(predicate);
    list.DataBind();

}