twig的 tests 学习

文章来源：http://twig.sensiolabs.org/doc/tests/index.html

做逻辑判断的。目前支持的有

divisibleby null even odd sameas constant defined empty

divisibleby

检查是否能被整除

{% if loop.index is divisibleby(3) %}
    ...
{% endif %}

{% if loop.index is divisibleby(3) %}
    ...
{% endif %}

null

{{ var is null }}

{{ var is null }}

even

变量是否是偶数

{{ var is even }}

{{ var is even }}

odd

变量是否是奇数

<PREclass=htmlname="code">{{ var is odd }}</PRE><BR>
<BR>
<P></P>
<PRE></PRE>
<P></P>
<H1><Aname=t4></A>sameas</H1>
<P>检查变量的地址是否相同</P>
<P><PREclass=htmlname="code">{% if foo.attribute is sameas(false) %}
    the foo attribute really is the ``false`` PHP value
{% endif %}</PRE><BR>
<BR>
<P></P>
<H1><Aname=t5></A>constant</H1>
<P>检查变量的值是否相同</P>
<P><PREclass=htmlname="code">{% if post.status is constant('Post::PUBLISHED') %}
    the status attribute is exactly the same as Post::PUBLISHED
{% endif %}</PRE><BR>
<BR>
<P></P>
<H1><Aname=t6></A>defined</H1>
<P>测试变量是否定义</P>
<P><PREclass=htmlname="code">{# defined works with variable names #}
{% if foo is defined %}
    ...
{% endif %}

{# and attributes on variables names #}
{% if foo.bar is defined %}
    ...
{% endif %}

{% if foo['bar'] is defined %}
    ...
{% endif %}</PRE><BR>
<BR>
<P></P>
<H1><Aname=t7></A>empty</H1>
<DIV>测试变量是否为空，empty的意思是：该变量已经定义，但他的值是 null false 或者是空字符串</DIV>
<DIVsizcache="1"sizset="9"><PREclass=htmlname="code">{# evaluates to true if the foo variable is null, false, or the empty string #}
{% if foo is empty %}
    ...
{% endif %}</PRE><BR>
<BR>
</DIV>