with

使用 with 创建一个新的内部范围。在此范围内设置的变量在范围外不可见：

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{% with %}
    {% set foo = 42 %}
    {{ foo }} {# foo is 42 here #}
{% endwith %}
foo is not visible here any longer

可以传递要在 with tag；上一个示例与下面的示例等效：

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{% with { foo: 42 } %}
    {{ foo }} {# foo is 42 here #}
{% endwith %}
foo is not visible here any longer

{# it works with any expression that resolves to a hash #}
{% set vars = { foo: 42 } %}
{% with vars %}
    ...
{% endwith %}

默认情况下，内部作用域可以访问外部作用域上下文；可以通过附加 only 关键字：

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{% set bar = 'bar' %}
{% with { foo: 42 } only %}
    {# only foo is defined #}
    {# bar is not defined #}
{% endwith %}