小编aja*_*jay的帖子

我从 Mohave 升级到 Big Sur，发现自制软件不再起作用。我使用命令安装了命令行工具

xcode-select --install

运行后brew list，出现以下错误

~ brew list
Traceback (most recent call last):
    11: from /usr/local/Homebrew/Library/Homebrew/brew.rb:23:in `<main>'
    10: from /usr/local/Homebrew/Library/Homebrew/brew.rb:23:in `require_relative'
     9: from /usr/local/Homebrew/Library/Homebrew/global.rb:37:in `<top (required)>'
     8: from /usr/local/Homebrew/Library/Homebrew/vendor/portable-ruby/2.6.3/lib/ruby/2.6.0/rubygems/core_ext/kernel_require.rb:54:in `require'
     7: from /usr/local/Homebrew/Library/Homebrew/vendor/portable-ruby/2.6.3/lib/ruby/2.6.0/rubygems/core_ext/kernel_require.rb:54:in `require'
     6: from /usr/local/Homebrew/Library/Homebrew/os.rb:3:in `<top (required)>'
     5: from /usr/local/Homebrew/Library/Homebrew/os.rb:21:in `<module:OS>'
     4: from /usr/local/Homebrew/Library/Homebrew/os/mac.rb:58:in `prerelease?'
     3: from /usr/local/Homebrew/Library/Homebrew/os/mac.rb:24:in `version'
     2: from /usr/local/Homebrew/Library/Homebrew/os/mac.rb:24:in `new'
     1: from /usr/local/Homebrew/Library/Homebrew/os/mac/version.rb:26:in `initialize'
/usr/local/Homebrew/Library/Homebrew/version.rb:368:in `initialize': Version value must be a string; got a NilClass () (TypeError)

我尝试删除文件夹/Library/Developer/CommandLineTools …

当我scala在终端上键入以启动repl时,它会抛出此错误

scala> [init] error: error while loading AnnotatedElement, 
class file '/usr/lib/jvm/java-8-oracle/jre/lib/rt.jar
(java/lang/reflect/AnnotatedElement.class)' 
is broken (bad constant pool tag 15 at byte 2713)

当我点击enter并输入时println("hello, world"),它再次抛出这个

error: error while loading CharSequence, 
class file '/usr/lib/jvm/java-8-oracle/jre/lib/rt.jar
(java/lang/CharSequence.class)' is broken
(bad constant pool tag 15 at byte 1501)

我正在使用Ubuntu 14.04并java -version给予

java version "1.8.0_05"
Java(TM) SE Runtime Environment (build 1.8.0_05-b13)
Java HotSpot(TM) 64-Bit Server VM (build 25.5-b02, mixed mode)

我正在使用Python解释器(Python 3.2.3)并尝试以下方法:

>>> dir(1)

这给了我int对象的所有属性和方法.接下来我尝试了:

>>> 1.__class__

然而,这引发了一个例外:

File "<stdin>", line 1
1.__class__
          ^
SyntaxError: invalid syntax

当我尝试使用浮子时,我得到了我的预期:

>>> 2.0.__class__
<class 'float'> 

为什么int和float文字表现不同？

我是一个C++新手.我在这里尝试了我的第一个程序.我的眼睛这个程序是正确的.

#include <iostream>

using namespace std;

class mystruct
{
    private:
        int m_a;
        float m_b;

    public:
        mystruct(int x, float y)
        {
                m_a = x;
                m_b = y;
        }

};


int main()
{

        mystruct m = mystruct(5,3.14);

        cout << "my structure " << m << endl;

        return 0;
}

但是我得到了很多错误.不知道为什么？

cout.cpp: In function ‘int main()’:
cout.cpp:26:29: error: no match for ‘operator<<’ in ‘std::operator<< [with _Traits = std::char_traits<char>]((* & std::cout), ((const char*)"my structure ")) << m’
cout.cpp:26:29: note: candidates are:
/usr/include/c++/4.6/ostream:110:7: note: std::basic_ostream<_CharT, …

我有一个MongoDB表格的文件集合

{
    "id": 42,
    "title": "candy can",
    "description": "canada candy canteen",
    "brand": "cannister candid",
    "manufacturer": "candle canvas"
}

我需要在输入搜索词中通过匹配除了以外的字段来实现自动完成功能id.例如,如果输入术语是can,那么我应该返回文档中的所有匹配单词

{ hints: ["candy", "can", "canada", "canteen", ...]

我看了这个问题,但没有帮助.我还尝试搜索如何regex在多个字段中搜索并提取匹配的标记,或在MongoDB中提取匹配的标记text search但找不到任何帮助.

我正在使用Flask扩展来为SQLAlchemy定义我的数据库模型.我希望id列是int类型并具有auto_increment属性但不使其成为主键.我该如何实现？

我试过这个:

from flask import Flask, jsonify
from flask.ext.sqlalchemy import SQLAlchemy

app = Flask(__name__)
app.config['SQLALCHEMY_DATABASE_URI'] = 'mysql://root:ajay@localhost/pydb'
app.config['SQLALCHEMY_ECHO'] = True
db = SQLAlchemy(app)

class Scenario(db.Model):
    scid = db.Column(db.Integer, nullable=False, unique=True, autoincrement=True)
    scenario_name = db.Column(db.String(100), primary_key=True)
    scenario_description = db.Column(db.String(200), nullable=False)
    image_id = db.Column(db.Integer, db.ForeignKey('images.id', onupdate='CASCADE', ondelete='CASCADE'))

    def __init__(self, scenario_name, scenario_description, image_id=None):
        self.scenario_name = scenario_name
        self.scenario_description = scenario_description
        self.image_id = image_id

    def __repr__(self):
        return '<Scenario %r, %r, %r>' % (self.scenario_name, self.scenario_description, self.image_id)

但是这不会将scid列设置为auto_increment.

我正在尝试实现Node.JS apn模块以连接到APNS(Apple推送通知服务),以便从运行Ubuntu 12.04的Amazon EC2实例上托管的节点服务器(使用ExpressJS)向iPhone设备发送通知.我收到此错误:

"Error: Cannot switch to old mode now.",
"    at emitDataEvents (_stream_readable.js:720:11)",
"    at ReadStream.Readable.resume (_stream_readable.js:705:3)",
"    at TLSSocket.<anonymous> (/home/ubuntu/usemebeta/routes/message.js:101:48)",
"    at TLSSocket.g (events.js:186:14)",
"    at TLSSocket.EventEmitter.emit (events.js:97:17)",
"    at TLSSocket.<anonymous> (_tls_wrap.js:579:16)",
"    at TLSSocket.EventEmitter.emit (events.js:97:17)",
"    at TLSSocket._finishInit (_tls_wrap.js:198:8)"

当我调用apn模块函数来推送通知时.但是,当我在文件中写入的函数中执行相同的操作并执行该文件时,它的工作正常.请帮忙.我该如何解决这个问题呢？

我想说清楚量角器VS ghostdriver之间的区别.

1. 用量角器:

   • 启动selenium web服务器进行测试.
   • 多个浏览器测试.
   • 无论何时开始测试,它都会打开浏览器.

2. 用ghostdriver:

   • 启动phantomjs web服务器.
   • 也可以配置多个浏览器.
   • 可与硒分开或与硒结合.

我的问题是PhantomJS webdriver可以单独运行,不需要selenium webdriver,多个浏览器和CI.为什么我们需要运行selenium并使用ghostdriver将selenium与phantomjs集成？

我想要offsetof()参数行mystruct1.我试过了

offsetof(struct mystruct1, rec.structPtr1.u_line.line) 

并且

offsetof(struct mystruct1, line)  

但都不起作用.

union {
    struct mystruct1 structPtr1;
    struct mystruct2 structPtr2;
} rec;

typedef struct mystruct1 {
    union {
        struct {
            short len;
            char buf[2];
        } line;

        struct {
            short len;
        } logo;

    } u_line;
};

我知道赋值是Python中的一个语句,即它不会像表达式那样求值.那么下面的代码行如何在Python中运行呢？请解释Python解释器内部发生的事情(lexing,解析,抽象语法树的形成).

# this works
spam = eggs = 'ham'

# this doesn't work. Throws SyntaxError
spam = (eggs = 'ham')