virtual

My programs run out of memory like half of the time I run them. Under Linux I can set a hard limit to the available memory using ulimit -v mem-in-kbytes. Actually, I use ulimit -S -v mem-in-kbytes, so I get a proper memory allocation problem in the program and I can abort. But... ulimit is not working in OSX 10.6. I've tried with -s and -m options, and they are not working. In 2008 there was some discussion about the same issue in MacRumors , but nobody proposed a good alternative. The should be a way a program can learn it's spending too much memory, or setting a limit through the OS. After

Why would you declare a method as "virtual". What is the benefit in using virtual? The Virtual Modifier is used to mark that a method\property(ect) can be modified in a derived class by using the override modifier. Example: class A { public virtual void Foo() //DoStuff For A } class B : A { public override void Foo() //DoStuff For B //now call the base to do the stuff for A and B //if required base.Foo() } Virtual allows an inheriting class to replace a method that the base class then uses. public class Thingy { public virtual void StepA() { Console.Out.WriteLine("Zing"); } public void Action(

So for creating files I use the following: fileHandle = open('fileName', 'w') then write the contents to the file, close the file. In the next step I process the file. At the end of the program, I end up with a "physical file" that I need to delete. Is there a way to write a "virtual" file that behaves exactly like a "physical" one (allowing it to be manipulated the same way) but does not exist at the end of the run in Python? You might want to consider using a tempfile.SpooledTemporaryFile which gives you the best of both worlds in the sense that it will create a temporary memory-based

继承 继承的一般形式 子类继承父类，是全盘继承，将父类所有的东西都继承给子类，除了父类的生死，就是父类的构造和析构是不能继承的。 继承的访问权限从两方面看： 1.对象：对象只能直接访问类中公有方法和成员。 2.继承的子类 私有继承就终止了父类再往下继承的能力 c++默认继承为私有继承 像以下程序 class D :public B1 ,public B2,public B3 公有继承B1，B2，B3 class D :public B1,B2,B3; 公有继承B1，私有继承B2,B3 继承是按照继承的顺序，和构造函数的初始化顺序无关,看以下程序 如果，子类中有对象成员，构造顺序是：1.父类，2.对象成员，3.自己 如果父类中有虚基类，应该先构造虚基类 虚基类 虚基类主要解决菱形继承问题，有以下程序 继承模型为： 内存模型： 如果对父类的x进行赋值，如下程序，会引发错误，编译器会报错，因为继承了两份，会产生二义性 如果指定访问A1还是A2就不会报错 内存中只为A1的成员x赋值了 如果希望来自父类的x在子类中只有1份 那么就要用虚拟继承 对于虚继承来的基类，又叫做虚基类 现在对cc.c进行赋值 A1和A2对象中的x成员都变成100 如果不是虚拟机成A1和A2继承来的x各自是各自的空间 虚继承让子类只保持父类的一份成员拷贝，A1和A2的继承的成员的空间是一个

面向对象的语言三大特点：封装、继承、多态 Ⅰ.封装：是把类的内部隐藏起来，以防止外部世界看见的一个面向对象的概念，通过关键字去控制变量，方法的访问权限。 1).访问修饰符： Ⅱ.继承： eg：我们建一个Person作为父类，Chinese作为子类 1 class Person 2 { 3 public string name="zhangsan"; 4 public int age=21; 5 //类里面有一个默认的构造方法，我们在下面写了一个构造方法，如果想去调用这个无参数的构造方法,那就要加一个无参构造方法 6 public Person() 7 { 8 Console.WriteLine("我是一个人类"); 9 } 10 public void SayHi() 11 { 12 Console.WriteLine("hello,我是人类！"); 13 } 14 } Person 1 class Chinese:Person 2 { 3 4 } Chinese 我们在程序入口里面调用父类里面的成员： class Program { static void Main(string[] args) { Chinese c = new Chinese(); Console.WriteLine(c.name); Console.WriteLine(c.age); c.SayHi();