Question

我有一个绑定定义如下：

<xforms:bind nodeset="instance( demo )/pointer"
                        type="xforms:integer"
                        calculate="
                        if($current-page &lt;  2 ) then  0 
                            else (
                            if($current-page &gt;  2 ) 
                            then ($max-pages - 1)
                            else .
                            )"/>

每次用户单击表单，当前页面值都会发生变化。我想了解一下上面绑定定义中的计算执行频率是多少？

问题是指针变量和当前页面相互依赖，因此如果我首先单击某个内容，则应立即评估指示器的值，在下一条指令中，我必须根据更改的指针值设置当前页面

<xforms:setvalue ref="$pointer"
                 value="($pointer + 1)"/>
<!-- i am assuming if the current-page is 2,
     it will increment, else the value is set as per calculate -->
<xforms:setvalue ref="$current-page"
                 value="($current-page + 1)"
                 xxforms:if="($pointer = $max-pages)" />

Answer 1

When users click on the button (assuming it is a button) that trigger the two xforms:setvalue, those xforms:setvalue run first and the xforms:bind calculate runs later.
Pretty much all users interaction with the form will cause the xforms:bind calculate to be be reevaluated.

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