Referencing a module by a ${}-Variable

[freeradius-mlist-users at m20.kunterbunt.de]

Hello all,

I am trying to set up a freeradius server with several mysql databases 
for different sets of accounts. The distinguation of the request should 
happen via the 'nas' table, which points to the different virtual servers.

So, in the directory "sites-enabled" I have a file defining several 
virtual servers:

     server wlan {
       instance_name = "wlan"
       $INCLUDE "../sites-available/instances_include"
     }

and within in the "instances_include" I want to refer to a separate 
instance of the SQL module:

         authorize {
                 filter_username
                 filter_password
                 preprocess
                 sql_instance_${.instance_name}
                 auth_log
         }

These modules are all defined in "mods-enabled":
     sql sql_instance_wlan {
       radius_db = "raddb_wlan"
       $INCLUDE "../mods-available/sql_instances_include"
     }

The problem here is, that the line "sql_instance_${.instance_name}" is 
not accepted during server startup:

including files in directory /etc/freeradius/3.0/sites-enabled/
including configuration file /etc/freeradius/3.0/sites-enabled/instances
including configuration file 
/etc/freeradius/3.0/sites-enabled/../sites-available/instances_include
/etc/freeradius/3.0/sites-enabled/../sites-available/instances_include[10]: 
Parse error after ".instance_name": unexpected token "}"
Errors reading or parsing /etc/freeradius/3.0/radiusd.conf

First I tried to use ${.name2}, which I hoped to refer to the section 
name "wlan". When this didn't worked, I defined a separate variable 
"instance_name".

I checked the files, that they have standard UNIX line termination and 
no additional ctrl characters.

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Starting - reading configuration files ...

Is there any possibility to refer to a module by a ${} variable?

Thanks for your attention and hopefully your help!

Kind regards,
Michael Sievert