promiseと読みやすさ

gistfile1.js

  // 1. thenまで一気に書くとthen節の中身が入れ子状に並ぶ。関数呼び出しが先頭に並ぶので読みやすいというか見慣れた形
  var filePath = "**/*.tpl";
  fetchTemplateFileList(filePath).then(function(fileList) {
    return Promise.all(_.map(fileList, function(filePath) {
      return createHtmlTextFromTemplateFile(filePath).then(function(htmlText) {
        return createTemplateTableFromHtmlText(htmlText).then(function(templateTable) {
          return createModuleTextFromTemplateTable(templateTable).then(function(moduleText) {
            return writeModuleFromText(moduleText, getOutFilePath(filePath)).then(function(result) {
              console.log("wrote "+ getOutFilePath(filePath));
            });
          });
        });
      });
    }));
  }).then(function(r) {
    console.log("all done");
  });
  

gistfile2.coffee

  # 2. coffee script版
  filePath = "**/*.tpl"
  fetchTemplateFileList(filePath).then (fileList) ->
    Promise.all(_.map fileList, (filePath) ->
      createHtmlTextFromTemplateFile(filePath).then (htmlText)  ->
        createTemplateTableFromHtmlText(htmlText).then (templateTable)  ->
          createModuleTextFromTemplateTable(templateTable).then (moduleText)  ->
            writeModuleFromText(moduleText, getOutFilePath filePath).then (result) ->
              console.log "wrote #{getOutFilePath filePath}"
    )
  .then (r) ->
    console.log "all done"

gistfile3.js

  // 3. Promiseの変数を用意してthenでチェーン。入れ子は浅くなるが読みやすいかというと。。
  var filePath = "**/*.tpl";
  var p = fetchTemplateFileList(filePath);
  p.then(function(fileList) {
    return Promise.all(_.map(fileList, function(filePath) {
      var p2 = createHtmlTextFromTemplateFile(filePath);
      p2.then(function(htmlText) {
        return createTemplateTableFromHtmlText(htmlText);
      }).then(function(templateTable) {
        return createModuleTextFromTemplateTable(templateTable);
      }).then(function(moduleText) {
        return writeModuleFromText(moduleText, getOutFilePath(filePath));
      }).then(function(result) {
        console.log("wrote "+ getOutFilePath(filePath));
      });
      return p2;
    }));
  }).then(function(r) {
    console.log("all done");
  });

gistfile4.coffee

  # 4. coffee script版
  filePath = "**/*.tpl"
  p = fetchTemplateFileList filePath
  p.then (fileList) ->
    Promise.all(_.map fileList, (filePath) ->
      p2 = createHtmlTextFromTemplateFile filePath
      p2.then (htmlText) ->
        createTemplateTableFromHtmlText htmlText
      .then (templateTable) ->
        createModuleTextFromTemplateTable templateTable
      .then (moduleText) ->
        writeModuleFromText moduleText, getOutFilePath filePath
      .then (result) ->
        console.log "wrote #{getOutFilePath filePath}"
      p2
    )
  .then (r) ->
    console.log "all done"