init

I have a singleton like this class Singleton: class __impl: def __init__(self): print "INIT" __instance = None def __init__(self): # Check whether we already have an instance if Singleton.__instance is None: Singleton.__instance = Singleton.__impl() # Store instance reference as the only member in the handle self.__dict__['_Singleton__instance'] = Singleton.__instance def __getattr__(self, attr): """ Delegate access to implementation """ return getattr(self.__instance, attr) def __setattr__(self, attr, value): """ Delegate access to implementation """ return setattr(self.__instance, attr,

Java程序运行时，必须经过编译和运行两个步骤。首先将后缀名为.java的源文件进行编译，最终生成后缀名为.class的字节码文件。然后Java虚拟机将编译好的字节码文件加载到内存（这个过程被称为类加载，是由加载器完成的），然后虚拟机针对加载到内存的java类进行解释执行，显示结果。 Java的运行原理 在Java中引入了虚拟机的概念，即在机器和编译程序之间加入了一层抽象的虚拟的机器。这台虚拟的机器在任何平台上都提供给编译程序一个的共同的接口。编译程序只需要面向虚拟机，生成虚拟机能够理解的代码，然后由解释器来将虚拟机代码转换为特定系统的机器码执行。在Java中，这种供虚拟机理解的代码叫做字节码（ByteCode），它不面向任何特定的处理器，只面向虚拟机。每一种平台的解释器是不同的，但是实现的虚拟机是相同的。Java源程序经过编译器编译后变成字节码，字节码由虚拟机解释执行，虚拟机将每一条要执行的字节码送给解释器，解释器将其翻译成特定机器上的机器码，然后在特定的机器上运行。 Java代码编译和执行的整个过程 Java代码编译是由Java源码编译器来完成，流程图如下所示： Java字节码的执行是由JVM执行引擎来完成，流程图如下所示： Java代码编译和执行的整个过程包含了以下三个重要的机制： Java源码编译机制 类加载机制 类执行机制 Java源码编译机制 Java

In the man page it appears that even if you initialise a semaphore to a value of one: sem_init(&mySem, 0, 1); It could still be incremented to a value greater than 1 with multiple calls to sem_post(&mySem); But in this code example the comment seems to think differently: sem_init(&mutex, 0, 1); /* initialize mutex to 1 - binary semaphore */ Is it possible to initialise a strictly binary semaphore in C? Note: The reason for doing this instead of using a mutex in this case is the sem_post and sem_wait may be called by different threads. If you want a strictly binary semaphore on Linux, I suggest

My Python IDE (pycharm) has stopped auto completing my modules (suggestions). I get unresolved references after every django module I try to import so: from django - works, however soon as I add a 'dot' it fails so from django.db import models gives me unresolved errors... The ackward thing is after compiling references DO work. I discovered that all my __init__.py files (everywhere) no longer are marked with python icon and are now notepad icons. Also opening init files in my interpreter gives non-color marked up text (no syntax highlighting). So I think Python doens't recognizes these files.

每个属性都有一个名称和值，他们都是字符串格式。属性被大量使用在Android系统中，用来记录系统设置或进程之间的信息交换。属性是在整个系统中全局可见的。每个进程可以get/set属性。 在系统初始化时，Android将分配一个共享内存区来存储的属性。这些是由“init”守护进程完成的，其源代码位于：device/system/init。“init”守护进程将启动一个属性服务。 属性服务在“init”守护进程中运行。每一个客户端想要设置属性时，必须连接属性服务，再向其发送信息。属性服务将会在共享内存区中修改和创建属性。任何客户端想获得属性信息，可以从共享内存直接读取。这提高了读取性能。客户端应用程序可以调用libcutils中的API函数以GET/SET属性信息。libcutils的源代码位于：device/libs/cutils。API函数是： int property_get(const char *key, char *value, const char *default_value); int property_set(const char *key, const char *value); 而libcutils又调用libc中的 __system_property_xxx 函数获得共享内存中的属性。libc的源代码位于：device/system/bionic。

I'm familiar with most of the process of creating an XIB for my own UIView subclass, but not everything is working properly for me - it's mostly to do with the IBOutlets linking up. I can get them to work in what seems like a roundabout way. My setup is this: I have MyClass.h and MyClass.m. They have IBOutlets for a UIView (called view) and a UILabel (called myLabel). I added the 'view' property because some examples online seemed to suggest that you need this, and it actually solved an issue where I was getting a crash because it couldn't find the view property, I guess not even in the UIView