webgen users - Mar 2007 - Creating a simple tag plugin

I want to create a tag processor that is activated by something like:

   {flickr: http://www.flickr.com/photos/censi/232006603/}

(it then downloads from flickr the description of the photo -- look
for example at http://www.dis.uniroma1.it/~acensi/category/sss06.html)

This is my flickr.rb:

load_plugin ''webgen/plugins/tags/tag_processor''
module Tags
  class FlickrTag < DefaultTag
     param ''url'', nil, ''Url of the photo on
Flickr.''
     register_tag ''flickr''

    def process_tag( tag, chain )
	url = param( ''url'' )
        ...
    end
  end
end


I get ''ERROR -- No default mandatory parameter specified for tag
''Tag/Flickr'' but set in < ... sss062.page>''

I can''t understand what''s wrong.


-- 
Andrea Censi
      "Life is too important to be taken seriously" (Oscar Wilde)
Web: http://www.dis.uniroma1.it/~censi

On 05.03.2007, at 23:01, Andrea Censi wrote:
> I want to create a tag processor that is activated by something like:
>
>    {flickr: http://www.flickr.com/photos/censi/232006603/}
>
> (it then downloads from flickr the description of the photo -- look
> for example at http://www.dis.uniroma1.it/~acensi/category/sss06.html)
>
> This is my flickr.rb:
>
> load_plugin ''webgen/plugins/tags/tag_processor''
> module Tags
>   class FlickrTag < DefaultTag
>      param ''url'', nil, ''Url of the photo on
Flickr.''
>      register_tag ''flickr''
>
>     def process_tag( tag, chain )
> 	url = param( ''url'' )
>         ...
>     end
>   end
> end
>
>
> I get ''ERROR -- No default mandatory parameter specified for tag
> ''Tag/Flickr'' but set in < ...
sss062.page>''
>
> I can''t understand what''s wrong.
You need to specify which parameter should be used as default  
mandatory parameter. webgen normally needs a YAML hash as argument to  
a tag, like this {myTag: {option: value, option2: value2}}. However,  
as some tags sometimes only have one mandatory parameter (eg. Tag/ 
Relocatable just needs to know the file it should make relocatable) I  
introduced the default mandatory parameter. This parameter always  
needs to have a value and can be set by using the shortcut {myTag:  
value}.

Just add the following under the "param ''url''..."
line:

set_mandatory ''url'', true

After that it will work!

Bye,
   Thomas