Argument ViewHelper <f:argument> 

f:argument allows to define requirements and type constraints to variables that are provided to templates and partials. This can be very helpful to document how a template or partial is supposed to be used and which input variables are required.

These requirements are enforced during rendering of the template or partial: If an argument is defined with this ViewHelper which isn't marked as optional, an exception will be thrown if that variable isn't present during rendering. If a variable doesn't match the specified type and can't be converted automatically, an exception will be thrown as well.

Note that f:argument ViewHelpers must be used at the root level of the template, and can't be nested into other ViewHelpers. Also, the usage of variables in any of its arguments is not possible (e. g. you can't define an argument name by using a variable).

Rendering of specific sections will not validate argument constraints. They will only be evaluated if the template or partial is rendered directly.

Go to the source code of this ViewHelper: ArgumentViewHelper.php (GitHub).