hexo 命令call是如何调用的

hexo.call

首先调用hexo对象中的call方法：

return hexo.call(cmd, args).then(function() {
     return hexo.exit();
   }).catch(function(err) {
     return hexo.exit(err).then(function() {
       handleError(err);
     });
   });

Hexo.prototype.call = function(name, args, callback){
	  if (!callback && typeof args === 'function'){
	    callback = args;
	    args = {};
	  }

	  var self = this;

	  return new Promise(function(resolve, reject){
	    var c = self.extend.console.get(name);

	    if (c){
	      c.call(self, args).then(resolve, reject);
	    } else {
	      reject(new Error('Console `' + name + '` has not been registered yet!'));
	    }
	  }).nodeify(callback);
};

注意到，通过self.extend.console.get(name)获取到的其实是个函数function，所以c.call(self,args)其实是调用的js自带的call函数。因为console.register的时候是放入的函数，注意var c = this.store[name.toLowerCase()] = fn;这句代码，关于注册命令的分析，我们已经在(hexo new命令解析)[https://johnwonder.github.io/2016/09/09/hexo-new/]中分析过。

所以这里的call就是调用的每个命令js文件中定义的函数，如plugins/console/new.js中定义的：

function newConsole(args){
  /* jshint validthis: true */
  // Display help message if user didn't input any arguments
  //console.log('参数是：'+args._);
  if (!args._.length){
    return this.call('help', {_: ['new']});
  }

  var data = {
    title: args._.pop(),//标题
    //这里layout就是可以通过 hexo n  title layout获取
    layout: args._.length ? args._[0] : this.config.default_layout,
    slug: args.s || args.slug,
    path: args.p || args.path
  };

  var keys = Object.keys(args);
  var key = '';
  var self = this;

  for (var i = 0, len = keys.length; i < len; i++){
    key = keys[i];
    if (!reservedKeys[key]) data[key] = args[key];
  }

  return this.post.create(data, args.r || args.replace).then(function(post){
    self.log.info('Created: %s', chalk.magenta(tildify(post.path)));
  });
 }

这里的this对象就是hexo本身，所以this.post就是hexo对象中定义的post变量：

Post.prototype.create = function(data, replace, callback){
  if (!callback && typeof replace === 'function'){
    callback = replace;
    replace = false;
  }

  var ctx = this.context;
  var config = ctx.config;

  data.slug = slugize((data.slug || data.title).toString(), {transform: config.filename_case});
  data.layout = (data.layout || config.default_layout).toLowerCase();
  data.date = data.date ? moment(data.date) : moment();

  return Promise.all([
    // Get the post path
    ctx.execFilter('new_post_path', data, {
      args: [replace],
      context: ctx
    }),
    // Get the scaffold
    this._getScaffold(data.layout)
  ]).spread(function(path, scaffold){
    // Split data part from the raw scaffold
    var split = yfm.split(scaffold);
    var separator = split.separator || '---';
    var jsonMode = separator[0] === ';';
    var frontMatter = prepareFrontMatter(_.clone(data));
    var content = '';

    // Compile front-matter with data
    var renderedData = swig.compile(split.data)(frontMatter);

    // Parse front-matter
    var compiled;

    if (jsonMode){
      compiled = JSON.parse('{' + renderedData + '}');
    } else {
      compiled = yaml.load(renderedData);
    }

    // Add data which are not in the front-matter
    var keys = Object.keys(data);
    var key = '';
    var obj = compiled;

    for (var i = 0, len = keys.length; i < len; i++){
      key = keys[i];

      if (!preservedKeys[key] && obj[key] == null){
        obj[key] = data[key];
      }
    }

    // Prepend the separator
    if (split.prefixSeparator) content += separator + '\n';

    content += yfm.stringify(obj, {
      mode: jsonMode ? 'json' : ''
    });

    // Concat content
    content += split.content;

    if (data.content){
      content += '\n' + data.content;
    }

    var result = {
      path: path,
      content: content
    };

    return Promise.all([
      // Write content to file
      fs.writeFile(path, content),
      // Create asset folder
      createAssetFolder(path, config.post_asset_folder)
    ]).then(function(){
      ctx.emit('new', result);
    }).thenReturn(result);
  }).nodeify(callback);
}