switch, case, default, break

Synopsis

<#switch value>
  <#case refValue1>
    ...
    <#break>
  <#case refValue2>
    ...
    <#break>
  ...
  <#case refValueN>
    ...
    <#break>
  <#default>
    ...
</#switch>

Where:

  • value, refValue1, etc.: Expressions evaluates to scalars of the same type.

The break-s and default are optional.

Description

The usage of this directive is not recommended, as it’s error-prone because of the fall-through behavior. Use elseif-s instead unless you want to exploit the fall-through behavior.

Switch is used to choose a fragment of template depending on the value of an expression:

Template 
<#switch animal.size>
  <#case "small">
     This will be processed if it is small
     <#break>
  <#case "medium">
     This will be processed if it is medium
     <#break>
  <#case "large">
     This will be processed if it is large
     <#break>
  <#default>
     This will be processed if it is neither
</#switch>

Inside the switch must be one or more <#case value>, and after all such case tags optionally one <#default>. When FM reaches the switch directive, it chooses a case directive where refValue equals with value and continues the processing of the template there. If there is no case directive with appropriate value then it continues processing at the default directive if that exists, otherwise it continues the processing after the end-tag of switch. And now comes the confusing thing: when it has chosen a case directive, it will continue the processing there, and will go ahead until it reaches a break directive. That is, it will not automatically leave the switch directive when it reaches another case directive or the <#default> tag. Example:

Template 
<#switch x>
  <#case 1>
    1
  <#case 2>
    2
  <#default>
    d
</#switch>

If x is 1, then it will print 1 2 d; if x is 2 then it will print 2 d; if x is 3 then it will print d. This is the mentioned fall-through behavior. The break tag instructs FM to immediately skip past the switch end-tag.

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