函数

机器翻译

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任务： 把一个计算写一次，在页面需要的任何地方使用。

yaml

# Recipe: a q:function, called from attributes and from the HTML.
paths:
  components: ./components

q:function 像动作一样接收 q:param：每次调用时，每个参数都会被转换成它的类型，并按它的规则检查；default 补上省略的参数。returnType 检查返回的值。函数可以在页面的任何表达式中调用，包括在另一个调用里面。

xml

<q:component name="Prices">
  <!-- Arguments are checked against the q:params on every call. -->
  <q:function name="withTax" returnType="number">
    <q:param name="amount" type="number" required="true" min="0" />
    <q:param name="rate" type="number" default="0.1" />
    <q:return value="{round(amount * (1 + rate), 2)}" />
  </q:function>

  <q:function name="label">
    <q:param name="amount" type="number" required="true" />
    <q:return value="{'free' if amount == 0 else '$' + str(amount)}" />
  </q:function>

  <q:set name="book" value="{withTax(20)}" />

  <html>
  <body>
    <p>Book: {label(book)}</p>
    <p>Food: {label(withTax(10, 0.05))}</p>
    <p>Sample: {label(withTax(0))}</p>
  </body>
  </html>
</q:component>

xml

<q:test name="a function called from q:set and from the HTML" page="/">
  <test:visit />
  <test:expect var="book" value="22.0" />
  <test:expect text="Book: $22.0" />
</q:test>

<q:test name="an argument by position replaces the default" page="/">
  <test:visit />
  <test:expect text="Food: $10.5" />
</q:test>

<q:test name="functions compose" page="/">
  <test:visit />
  <test:expect text="Sample: free" />
</q:test>

text

tests/prices.test.q
  PASS  a function called from q:set and from the HTML
  PASS  an argument by position replaces the default
  PASS  functions compose
3 passed, 0 failed

参见 FN-1、FN-3 和 FN-4。

函数 ​

函数