小编pet*_*huk的帖子

如何在一行中做出这个声明？

if x is not None:
    if x > 0:
        pass

如果我只用“和”写，如果没有，它会显示异常

if x is not None and x > 0:
     pass

我有个问题.我想从"Game"类中调用"gameWindow"的构造函数.问题是,如果我从构造函数中调用它,它将初始化为局部变量(示例A),如果我将其定义为私有成员 - 我不能使用构造函数的参数.如何将gamewindowObj作为构造函数的成员？

//示例А

class Game{
public:
    Game(int inWidth, int inHeight, char const * Intitle);
};

Game::Game(int inWidth, int inHeight, char const * Intitle){
    gameWindow gamewindowObj=gameWindow(inWidth, inHeight, Intitle);
}

//示例В

class Game{
public:
    Game(int inWidth, int inHeight, char const * Intitle);
private:
    gameWindow gamewindowObj=gameWindow(inWidth, inHeight, Intitle);
};
Game::Game(int inWidth, int inHeight, char const * Intitle){}

尝试在系统中安装具有不同版本的django，它向我显示：

Installing collected packages: Django
Found existing installation: Django 1.7.11
Not uninstalling django at /home/user/lib/python2.7, outside environment /home/user/webapps/v2_dev/venv

成功安装Django-1.8.19

但实际上有旧版本

尝试了不同的命令：

./venv/bin/pip install Django==1.8.11

pip install Django==1.8.11

更新：安装软件包时，它显示：

The required version of setuptools (>=16.0) is not available,
and can't be installed while this script is running. Please
install a more recent version first, using
'easy_install -U setuptools'.
(Currently using setuptools 3.1 (/home/user/lib/python2.7/setuptools-3.1-py2.7.egg))

升级时：

venv/bin/pip install --upgrade setuptools
Requirement already up-to-date: setuptools in ./venv/lib/python2.7/site-packages (40.5.0)