增量吞咽式少构建

Question

在我的办公室里，我们正在使用gulp来构建更少的文件。我想改进构建任务，因为它花了一秒的时间来构建我们最近从事的一个大型项目。这样做的目的是缓存文件，并且只传递更改后的文件。因此，我从google开始，找到了用于javascript的增量构建，并认为用更少的代价重写它们是很容易的。下面是我的第一篇文章：https://github.com/gulpjs/gulp/blob/master/docs/recipes/incremental-builds-with-concatenate.md

在几次失败的尝试之后，我得到了以下代码(用最新的引导发行版进行了测试)：

var gulp            = require('gulp');
var less            = require('gulp-less');
var concat          = require('gulp-concat');
var remember        = require('gulp-remember');
var cached          = require('gulp-cached');

var fileGlob = [
    './bootstrap/**/*.less',
    '!./bootstrap/bootstrap.less',
    '!./bootstrap/mixins.less'
];

gulp.task('less', function () {
    return gulp.src(fileGlob)
        .pipe(cached('lessFiles'))
        .pipe(remember('lessFiles'))
        .pipe(less())
        .pipe(gulp.dest('output'));
});

gulp.task('watch', function () {
    var watcher = gulp.watch(fileGlob, ['less']);
    watcher.on('change', function (e) {
        if (e.type === 'deleted') {
            delete cached.caches.scripts[e.path];
            remember.forget('lessFiles', e.path);
        }
    });
});

但是这只传递更改的文件，而较少的编译器由于缺少变量定义而失败。如果我在完成较少的任务之前将连接插件排成管道，那么gulp就会陷入一个(看似没完没了的)循环中。

gulp.task('less', function () {
    return gulp.src(fileGlob)
        .pipe(cached('lessFiles'))
        .pipe(remember('lessFiles'))
        .pipe(concat('main.less')
        .pipe(less())
        .pipe(gulp.dest('output'));
});

有没有人有使用这些插件的经验，或者设法以另一种方式创建一个增量的、更少的构建。下面是一个用于测试的github存储库：https://github.com/tuelsch/perfect-less-build

PS:我计划在后面添加皮棉，源地图，小型化，特别是缓存破坏和自动修复。

Answer 1

和Ashwell一样，我发现使用导入来确保所有较少的文件都能够访问它们所需的变量和混合文件是很有用的。我还在导入时使用了一个更少的文件，用于捆绑。这有几个优点：

1. 我可以利用another的特性来做一些复杂的事情，比如重写变量值来生成多个主题，或者在另一个更少的文件中的每个规则前加上一个类。
2. 不需要连接插件。
3. 像Visual的这样的工具可以提供语法帮助和输出预览，因为每个较少的文件都完全能够由自己呈现。

如果您希望导入变量、混合文件等，但不希望实际输出另一个文件的全部内容，则可以使用：

@import (reference) "_colors.less";

经过几天的努力，我终于能够得到一个增量构建，它正确地重新构建了所有依赖于我更改的较少文件的对象。我记录了结果here。这是最后一个吞咽文件：

/*
 * This file defines how our static resources get built.
 * From the StaticCommon root folder, call "gulp" to compile all generated
 * client-side resources, or call "gulp watch" to keep checking source 
 * files, and rebuild them whenever they are changed. Call "gulp live" to 
 * do both (build and watch).
 */

/* Dependency definitions: in order to avoid forcing everyone to have 
 * node/npm installed on their systems, we are including all of the 
 * necessary dependencies in the node_modules folder. To install new ones,
 * you must install nodejs on your machine, and use the "npm install XXX" 
 * command. */
var gulp = require('gulp');
var less = require('gulp-less');
var LessPluginCleanCss = require('less-plugin-clean-css'),
    cleanCss = new LessPluginCleanCss();
var sourcemaps = require('gulp-sourcemaps');
var rename = require('gulp-rename');
var cache = require('gulp-cached');
var progeny = require('gulp-progeny');
var filter = require('gulp-filter');
var plumber = require('gulp-plumber');
var debug = require('gulp-debug');

gulp.task('less', function() {
    return gulp
        // Even though some of our LESS files are just references, and 
        // aren't built, we need to start by looking at all of them because 
        // if any of them change, we may need to rebuild other less files.
        .src(
        ['Content/@(Theme|Areas|Css)/**/*.less'],
        { base: 'Content' })
        // This makes it so that errors are output to the console rather 
        // than silently crashing the app.
        .pipe(plumber({
            errorHandler: function (err) {
                console.log(err);
                // And this makes it so "watch" can continue after an error.
                this.emit('end');
            }
        }))
        // When running in "watch" mode, the contents of these files will 
        // be kept in an in-memory cache, and after the initial hit, we'll
        // only rebuild when file contents change.
        .pipe(cache('less'))
        // This will build a dependency tree based on any @import 
        // statements found by the given REGEX. If you change one file,
        // we'll rebuild any other files that reference it.
        .pipe(progeny({
            regexp: /^\s*@import\s*(?:\(\w+\)\s*)?['"]([^'"]+)['"]/
        }))
        // Now that we've set up the dependency tree, we can filter out 
        // any files whose
        // file names start with an underscore (_)
        .pipe(filter(['**/*.less', '!**/_*.less']))
        // This will output the name of each LESS file that we're about 
        // to rebuild.
        .pipe(debug({ title: 'LESS' }))
        // This starts capturing the line-numbers as we transform these 
        // files, allowing us to output a source map for each LESS file 
        // in the final stages.
        // Browsers like Chrome can pick up those source maps and show you 
        // the actual LESS source line that a given rule came from, 
        // despite the source file's being transformed and minified.
        .pipe(sourcemaps.init())
        // Run the transformation from LESS to CSS
        .pipe(less({
            // Minify the CSS to get rid of extra space and most CSS
            // comments.
            plugins: [cleanCss]
        }))
        // We need a reliable way to indicate that the file was built
        // with gulp, so we can ignore it in Mercurial commits.
        // Lots of css libraries get distributed as .min.css files, so
        // we don't want to exclude that pattern. Let's try .opt.css 
        // instead.
        .pipe(rename(function(path) {
            path.extname = ".opt.css";
        }))
        // Now that we've captured all of our sourcemap mappings, add
        // the source map comment at the bottom of each minified CSS 
        // file, and output the *.css.map file to the same folder as 
        // the original file.
        .pipe(sourcemaps.write('.'))
        // Write all these generated files back to the Content folder.
        .pipe(gulp.dest('Content'));
});

// Keep an eye on any LESS files, and if they change then invoke the 
// 'less' task.
gulp.task('watch', function() {
    return gulp.watch('Content/@(Theme|Areas|Css)/**/*.less', ['less']);
});

// Build things first, then keep a watch on any changed files.
gulp.task('live', ['less', 'watch']);

// This is the task that's run when you run "gulp" without any arguments.
gulp.task('default', ['less']);

现在我们只需运行gulp live来构建所有较少的文件一次，然后允许每个后续的更改只构建依赖于已更改的文件的文件。

Answer 2

因此，当我想在gulp中进行增量构建时，我通过抽象出gulp任务的内部过程来实现它，这样我就不必担心缓存的保存。

// Create a function that does just the processing
var runCompile = function( src, dest, opts ){
  return gulp.src( src )
    .pipe(less( opts ))
    .pipe(gulp.dest( dest ));
};

// Leverage the function to create the task
gulp.task( 'less', function(){
  return runCompile( fileGlob, 'output', {} );
});

// Use it again in the watch task
gulp.task( 'less:watch', function(){
  return gulp.watch( fileGlob )
    .on( "change", function( event ){
      // might need to play with the dest dir here
      return runCompile( event.path, 'output', {} );
    });
});

这对我很有用，我在我的任务中都使用了这个模式。然而，我已经注意到，有时吞咽会挤压路径在手表“上的变化”，如果它得到一个文件。在这种情况下，我自己操作路径，类似于path.dirname(srcPath.replace( srcDir, outputDir ))作为runCompile函数的参数dest。

编辑:刚刚意识到这可能不会解决你的“丢失变量”问题。我没有任何头绪来解决这个问题，因为我大量使用导入来组织较少的文件，所以每个需要一组变量的文件都会有一个import语句，确保它们在那里。

Answer 3

我们实际上可以使用新的gulp-progeny-mtime和gulp来完成这个任务。Stripling所采用的方法几乎是最好的方法，每次您运行expect任务时，它都会从头开始编译所有内容，然后开始查看文件。如果您使用的样式表较少，这将花费您大量时间。gulp-progeny-mtime类似于吞食后代的，只不过它做的是真正的硬核东西。每当一个文件通过gulp-progeny-mtime，时，它都会检查导入中的任何修改，如果是的话，它将调整流中当前文件的mtime，这将导致它通过gulp更新的。我觉得这样更好，因为我们甚至没有缓存任何东西。

   //Compile less for deployment 
   gulp.task("less", () => {
      return gulp
        .src(["static/less/**/*.less"])
        .pipe(progenyMtime())
        .pipe(
          plumber({
            errorHandler: function (err) {
              log(chalk.bgRed.white.bold(err.message));
            },
          })
        )
        .pipe(filter(["**/*.less", "!**/_*.less", "!static/less/includes*/**"]))
        .pipe(newer({ dest: "static/css/", ext: ".css" }))
        .pipe(debug({ title: "LESS" }))
        .pipe(
          less({
            plugins: [cleanCss, autoprefix],
          })
        )
        .pipe(gulp.dest("static/css/"));
    });

    //Watch changes is less and compile if changed.
    gulp.task("watch-less", () => {
      return gulp.watch("static/less/**/*.less", gulp.series("less"));
    });
    
    //Compile all less files on first run ( if changed ) then compile only modified files from next run
    gulp.task("live-less", gulp.series("less", "watch-less"));