2.9. 表达式工具

表达式工具是一种类型的流程 (process), 可单独运行，或作为工作流的一个步骤运行。它执行纯 JavaScript 表达式，意在隔离复杂的 JavaScript 表达式，以对输入数据进行运算，并生成结果作为输出。

Similar to the command-line tool it requires inputs and outputs. But instead of baseCommand, it requires an expression attribute.

CWL 表达式工具。

uppercase.cwl

cwlVersion: v1.2
class: ExpressionTool

requirements:
  InlineJavascriptRequirement: {}

inputs:
  message: string
outputs:
  uppercase_message: string

expression: |
  ${ return {"uppercase_message": inputs.message.toUpperCase()}; }

备注

We had to use an InlineJavascriptRequirement as our expression contains a JavaScript call in .toUpperCase(). This means to tools using the expression tool that JavaScript is a requirement.