define variables by vhost only

Hello List,

iam looking for a way to use define to create variables limited to
vhosts (apache 2.4).
Currently i have some vhosts and use this syntax:

define myvar mycontent.

Name of variables is in all vhosts the same, "mycontent" is different
and vhost related. Later i use this variable in .htaccess files for users:

Addhandler ${myvar} .php

Unfortunately define-directive defines the variable for complete server
and not to vhost only. so content of "myvar" gets overwritten with every
following vhost-config.
So if user A uses this variable, he sees content of variable created in
vhost for user z.

Is there a possibility to use variables limited to vhost but can be used
the same way in .htaccess files? I think setenv seems not suitable for this.