new problem : )

my funtion

	function showPDF($id) {
		$record = DataObject::get_by_id("File", $id);
		return $record;
	}

in template

        <% if PDFID %>
		<% control showPDF() %>
		<a href="$Filename"><img src="/themes/tutorial/images/pdf_ikon.gif" width="32" height="32" /></a> 
		<% end_control %>
        <% end_if %>

and everything works great when i execute showPDF like this: <% control showPDF(204) %>
but when i have: <% control showPDF($PDFID) %> i got an error:

Parse error: syntax error, unexpected '}' in C:\Windows\Temp\silverstripe-cacheC--serwer-strony-ernesto\.cacheC..serwer.strony.ernesto.themes.tutorial.templates.Layout.EnPielgrzymkaPage.ss on line ....

$PDFID is variable form database

As it says on the documentation page for templates - passing dynamic variables into functions is not supported yet.

ok it works now but i cant use it in other <% control %>

If you want to use the $replace_str on other page controllers other then the OkolicaMapaPage_Controller then it has to be in the model - OkolicaMapaPage class. Controllers aren't passed along when doing controls of other pages.