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ActionWidget Execution Modes

New in: 5.2.0 The default behaviour of action widgets has some peculiarities that often cause confusion. There is now an improved mode that simplifies how things work, but due to BackwardsCompatibility constraints, it must be explicitly engaged in order to take advantage of it.

The peculiarities relate to the way that the results of previous action widgets are available to subsequent action widgets. By default, action widgets are refreshed before each execution which ensure that they reflect the results of previous actions. However, ordinary widgets are not updated in the same way.

In the following contrived example, a button triggers a series of actions that should result in the string foo being assigned to the text field of the tiddler ActionTestTiddler. However, it fails to produce the expected result because the <$set> widget is not refreshed with the new value of ActionTestTiddler after the execution of the first <$action-setfield> widget.

\define actions()
<$action-setfield $tiddler="ActionTestTiddler" $field="text" $value="FOO"/>
<$set name="newvalue" value={{{ [{ActionTestTiddler}lowercase[]] }}}>
<$action-setfield $tiddler="ActionTestTiddler" $field="text" $value=<<newvalue>>/>
</$set>
\end

Current value of ActionTestTiddler: {{ActionTestTiddler}}

<$button actions=<<actions>>>
Click me
</$button>

That renders as:

Current value of ActionTestTiddler:

The new behaviour avoids these problems by refreshing all widgets before execution, not just action widgets. It is engaged by running the actions in a scopr that includes the variable tv-action-refresh-policy set to the value always.

This can be done within an action string, or via a local variable declaration containing the widget triggering the action.

Do not attempt to set tv-action-refresh-policy globally; the core will only work correctly with the default setting

The example above works as expected with the addition of tv-action-refresh-policy:

\define tv-action-refresh-policy() always

\define actions()
<$action-setfield $tiddler="ActionTestTiddler" $field="text" $value="FOO"/>
<$set name="newvalue" value={{{ [{ActionTestTiddler}lowercase[]] }}}>
<$action-setfield $tiddler="ActionTestTiddler" $field="text" $value=<<newvalue>>/>
</$set>
\end

Current value of ActionTestTiddler: {{ActionTestTiddler}}

<$button actions=<<actions>>>
Click me
</$button>

That renders as:

Current value of ActionTestTiddler: