小编Mil*_*šić的帖子

我在跨范围的Sass中使用变量默认值时遇到问题.我的测试例子是:

@mixin foo { 
        $val: 'red' !default; 
        .bar { 
                color: $val; 
        } 

} 

@include foo; 
.class1 { 
        $val: 'green'; 
        @include foo; 
        .class11 { 
                @include foo; 
        } 
} 

$val: 'black'; 
.class2 { 
        @include foo; 
} 

.class3 { 
        $val: 'blue'; 
        @include foo; 
} 

.class4 { 
        @include foo; 

}

它编译为:

.bar { 
  color: "red"; 

} 

.class1 .bar { 
  color: "red"; 
} 

.class1 .class11 .bar { 
  color: "red"; 
} 

.class2 .bar { 
  color: "black"; 
} 

.class3 .bar { 
  color: "blue"; 
} 

.class4 .bar { …

该文档声明您可以直接使用池:

pool.query();

或手动获取连接,然后运行查询:

pool.getConnection(function(err, connection) {
  // Use the connection
  connection.query( 'SELECT something FROM sometable', function(err, rows) {
    // And done with the connection.
    connection.release();

    // Don't use the connection here, it has been returned to the pool.
  });
});

第二个选项是每次需要运行查询时都必须重复的许多代码.直接使用游泳池是否安全？完成后,是否pool.query()将连接释放回池中？

"SELECT ... FOR UPDATE"锁是否在MySQL中加入了行？

如果是这样,是否可以禁用此行为？

文档中没有任何相关内容.我已经看到Oracle支持"SELECT ... FOR UPDATE OF table_name"table_name是主表或者受影响的行将被锁定的连接表之一,但我从来没有在MySQL的上下文中看到这一点.

有谁知道是否可以使用EventSource发送基本的http身份验证凭据？

启用了InnoDB插件的MySQL Server版本5.1.41.我有以下三张发票表:发票,invoice_components和invoice_expenses.表发票具有invoice_id主键.invoice_components和invoice_expenses都链接到表发票,其invoice_id为非唯一foreign_key(每张发票可以包含多个组件和多个费用).两个表都具有此外键的BTREE索引.

我有以下交易:

交易1

START TRANSACTION; 
SELECT * FROM invoices WHERE invoice_id = 18 FOR UPDATE; 
SELECT * FROM invoice_components WHERE invoice = 18 FOR UPDATE; 
SELECT * FROM invoice_expenses WHERE invoice = 18 FOR UPDATE; 

对于第一个事务,一切正常,并且选择并锁定行.

交易2

START TRANSACTION; 
SELECT * FROM invoices WHERE invoice_id = 19 FOR UPDATE; 
SELECT * FROM invoice_components WHERE invoice = 19 FOR UPDATE; 
SELECT * FROM invoice_expenses WHERE invoice = 19 FOR UPDATE; 

第二个事务返回ERROR 1205 (HY000): Lock wait timeout exceeded; try restarting …

一个例子是一个通用的寄存器文件,我试图像这样实现:

entity register_file is
generic(reg_width: integer := 32; reg_num: integer := 16);
constant sel_num: integer := integer(CEIL(LOG(Real(reg_num))));
port (
    data_in: in std_logic_vector(reg_width - 1 downto 0);
    data_out: out std_logic_vector(reg_width - 1 downto 0);
    rd_sel: in std_logic_vector(sel_num - 1 downto 0);
    wr_sel: in std_logic_vector(sel_num - 1 downto 0);
    rd_enable: in std_logic;
    wr_enable: in std_logic;
    clock: in std_logic;
);
end register_file;

这不起作用,因为它似乎是通用的,端口必须是前两个声明,其次是其他声明.如果我在端口声明后移动type和constant,则在处理端口声明时它们不可见.

我是VHDL的新手,我认为这应该是一个常见的问题,但我找不到解决方案.显然,我想避免使用复制粘贴解决方案.

我正在尝试让webpack为React项目输出正确的源图,该项目使用CommonsChunkPlugin拆分为应用程序和供应商块,并使用UglifyJsPlugin缩小.这是针对生产环境的,所以我:

• 不希望生成供应商包的巨大源图.
• 不想在地图文件中使用webpack://来源
• 不想要css的地图文件
• 需要实际的映射文件输出并从js文件链接到,以便错误监视工具可以加载它

所有这些对于devtool配置选项来说似乎有点太多了,所以我试图直接使用devtool:false来使用SourceMapDevToolPlugin.

webpack配置的相关部分如下所示:

entry: production ? {
    app: './src/index.jsx',
    vendor: Object.keys(packageDotJson.dependencies)
} : './src/index.jsx',

output: {
    path: production ? './dist' : './assets',
    publicPath: production ? '' : '/',
    filename: production ? 'app.[hash].js' : 'app.js'
},

plugins: production ? [
    new webpack.optimize.CommonsChunkPlugin(/* chunkName= */"vendor", /* filename= */"vendor.bundle.[hash].js"),
    new webpack.optimize.DedupePlugin(),
    new webpack.optimize.UglifyJsPlugin({
        compress: {
            warnings: false
        }
    }),
    new ExtractTextPlugin("app.[hash].css"),
    new webpack.SourceMapDevToolPlugin({
        test: [/\.js$/, /\.jsx$/],
        filename: "app.[hash].js.map",
        append: "//# sourceMappingURL=[url]",
        moduleFilenameTemplate: "[absolute-resource-path]",
        fallbackModuleFilenameTemplate: "[absolute-resource-path]",
        columns: false
    }),
    new …

phpPgAdmin的旧更改日志说有一个用于创建和编辑复合类型的界面,但我无法在任何地方找到它.在phpPgAdmin中是否有这个GUI？

我正在为我的设计编写一个通用测试平台,通过漂亮的标准总线与RAM通信.我咨询了一些例子并写成这样:

signal memory: mem_array;
signal mem_address: std_logic_vector(31 downto 0);
signal mem_data: std_logic_vector(31 downto 0);
signal mem_read: std_logic;
signal mem_write: std_logic;

cpu_mem_data <= transport memory(to_integer(unsigned(mem_address))) after DELAY when mem_read = '1' else (others => 'Z');

always : PROCESS
    file in_file: text open read_mode is "in.txt";
    variable line_str: line;
    variable address: std_logic_vector(31 downto 0);
    variable data: std_logic_vector(31 downto 0);
BEGIN
    reset <= '1';

    readline(in_file, line_str);
    hread(line_str, address);
    starting_pc <= address;
    while not endfile(in_file) loop
        readline(in_file, line_str);
        hread(line_str, address);
        read(line_str, data);
        memory(to_integer(unsigned(address))) <= …