UBK:IF

This tag is an implementation of common

if (test) then
  <block>
[else
  <block>
] end if 

control structure. The else part is optional, while the then and the test are mandatory. Into then and else, you can put everything you want (until it's XML).

The tag can be used in two ways:

<ubk:if test="php_condition">
  <ubk:then>
  ...
  </ubk:then>
  <ubk:else>
  ...
  </ubk:else>
</ubk:if>

or

<ubk:if>
  <ubk:test>php_condition</ubk:test>
  <ubk:then>
  ...
  </ubk:then>
  <ubk:else>
  ...
  </ubk:else>
</ubk:if>

The two are really equivalent; i prefer the second just when the condition is long or needs a bit of computation.

php_condition is a php expression that evaluates to a boolean, so almost any expression; you can express it in basically two different ways:

<ubk:if test="isset($GLOBALS['myvar'])">
  <ubk:then>hello <b>world</b>!</ubk:then>
</ubk:if>

or

<ubk:if>
  <ubk:test>
    $n = count($GLOBALS['myarray']);
    return ($n &gt; 5 and $n &lt; 10);
  </ubk:test>
  <ubk:then>hello <b>world</b>!</ubk:then>
</ubk:if>

The point is that the framework adds return and the ending semicolon if they are missing.

UBK:WHEN

This very flexible tag implements a multi-control control structure, with two different behaviours based on the value of the boolean attribute tutte. When tutte is true (default behaviour), the tag acts like this:

if (test_1) then
  <block>
[else
  <block>
] end if
[if (test_2) then
  <block>
[else
  <block>
] end if]
...
[if (test_n) then
  <block>
[else
  <block>
] end if]

When tutte is false, instead:

if (test_1) then
  <block>
[else
  [<block>]
  if (test_2) then
    <block>
  [else
    [<block>]
  ... ] end if
] end if

that means:

go to next test
if _test_ is positive
  then display its _then_ block
  else
    if exists a corresponding _else_ block, display it
    restart iteration

Writing it down with a single, last else block, with tutte to false, it is equivalent to a

if (test_1) then
  <block>
else if (test_2) then
  <block>
...
else
  <block>
end if

structure.

Here are a couple of examples:

<ubk:when tutte="true">

  <ubk:test>canDo('bau')</ubk:test>
  <ubk:then>bau</ubk:then>
  <ubk:else>not a dog !</ubk:else>

  <ubk:test>canDo('miao')</ubk:test>
  <ubk:then>miao</ubk:then>
  <ubk:else>not a cat !</ubk:else>

  <ubk:test>canDo('snort')</ubk:test>
  <ubk:then>snort</ubk:then>
  <ubk:else>not a dragon !</ubk:else>

</ubk:when>


<ubk:when tutte="false">

  <ubk:test>$GLOBALS['n'] &lt; 10</ubk:test>
  <ubk:then>small</ubk:then>

  <ubk:test>$GLOBALS['n'] &lt; 20</ubk:test>
  <ubk:then>normal</ubk:then>

  <ubk:else>big</ubk:else>
</ubk:when>

<ubk:when tutte="false">

  <ubk:test>$GLOBALS['n'] &lt; 10</ubk:test>
  <ubk:then>small</ubk:then>
  <ubk:else>not small: i'm </ubk:else>

  <ubk:test>$GLOBALS['n'] &gt 10</ubk:test>
  <ubk:then>big</ubk:then>
  <ubk:else>ten</ubk:else>

</ubk:when>

Same rules as UBK:IF are valid for test, then and else sub-tags.

UBK:SWITCH

This is an implementation of common switch control structure: a sequence of cases with corresponding blocks to be written if the case matches the test expression, with an optional default (else) block when no case is matched.

<ubk:switch>

  <ubk:test>$GLOBALS['myvar']</ubk:test>

  <ubk:case>'A'</ubk:case>
  <ubk:then>
    Hey, I'm the first ... and uppercase !
  </ubk:then>

  <ubk:case>'z'</ubk:case>
  <ubk:then>
    Hey, I'm the last ... and lowercase :(
  </ubk:then>

  <ubk:else>
    Unuseful middleware ...
  </ubk:else>

</ubk:switch>