gulp some tips

　　gulp作为替代grunt的task runner后起之秀，基于nodejs的stream操作模型，大大减少了对磁盘的操作因此大大提高了性能。

gulp error handling

var gulp = require('gulp');
var coffee = require('gulp-coffee');
var concat = require('gulp-concat');
function handleError(error){
  console.log(error);
  this.emit('end');
}
gulp.task('coffee',function(){
    return gulp.src('src/*.coffee')
                     .pipe(coffee())
                     .on('error',handleError)
                     .pipe(concat('all.js').pipe(gulp.dest('dist/'));
});
gulp.task('watch', ['coffee'], function(){
           gulp.watch('src/*.coffee',['coffee']);
});

对于gulp.src这类的对glob文件系统的操作，如果文件或者文件夹不存在，后续的gulp stream操作默认也不会有任何错误抛出，有时很让人困惑。

其中的解决方案就是使用gulp-expect-file

var coffee = require('gulp-coffee');
var expect = require('gulp-expect-file');

gulp.task('mytask', function() {
  var files = ['idontexist.html'];

  return gulp.src(files)
    .pipe(expect(files))
    .pipe(coffee());
});

http://stackoverflow.com/questions/22343591/gulp-silently-failing-no-errors-printed-to-console

下面通过重载gulp.src的方法实现默认将plumber放到gulp stream errorhandlering中

var gulp = require('gulp');
var plumber = require('gulp-plumber');
var gutil = require('gulp-util');

var gulp_src = gulp.src;
gulp.src = function() {
  return gulp_src.apply(gulp, arguments)
    .pipe(plumber(function(error) {
      // Output an error message
      gutil.log(gutil.colors.red('Error (' + error.plugin + '): ' + error.message));
      // emit the end event, to properly end the task
      this.emit('end');
    })
  );
};

https://www.timroes.de/2015/01/06/proper-error-handling-in-gulp-js/