在命名空间
它有一段奇怪的代码块:
MS.Internal
中,有一个名为NamedObject
的类。它有一段奇怪的代码块:
public override string ToString()
{
if (_name[0] != '{')
{
// lazily add {} around the name, to avoid allocating a string
// until it's actually needed
_name = String.Format(CultureInfo.InvariantCulture, "{{{0}}}", _name);
}
return _name;
}
我对这个评论特别感兴趣:
// lazily add {} around the name, to avoid allocating a string
// until it's actually needed
_name = String.Format(CultureInfo.InvariantCulture, "{{{0}}}", _name);
那怎么是“懒惰”的呢?它的懒惰程度如何影响其功能?
参考源码中的完整类:
//----------------------------------------------------------------------------
//
// <copyright file="NamedObject.cs" company="Microsoft">
// Copyright (C) Microsoft Corporation. All rights reserved.
// </copyright>
//
// Description: Placeholder object, with a name that appears in the debugger
//
//---------------------------------------------------------------------------
using System;
using System.Globalization;
using MS.Internal.WindowsBase;
namespace MS.Internal
{
/// <summary>
/// An instance of this class can be used wherever you might otherwise use
/// "new Object()". The name will show up in the debugger, instead of
/// merely "{object}"
/// </summary>
[FriendAccessAllowed] // Built into Base, also used by Framework.
internal class NamedObject
{
public NamedObject(string name)
{
if (String.IsNullOrEmpty(name))
throw new ArgumentNullException(name);
_name = name;
}
public override string ToString()
{
if (_name[0] != '{')
{
// lazily add {} around the name, to avoid allocating a string
// until it's actually needed
_name = String.Format(CultureInfo.InvariantCulture, "{{{0}}}", _name);
}
return _name;
}
string _name;
}
}
// File provided for Reference Use Only by Microsoft Corporation (c) 2007.
// Copyright (c) Microsoft Corporation. All rights reserved.
ToString()
才会生成,所以它被认为是懒惰的。你可以将“lazy”理解为“按需”的意思。 - Frédéric HamidiNamedObject
的实现者使用封装来保证对象的行为符合预期,并在某些情况下节省一些性能。 - KABoissonneault