Dynamically add subdir in a Qt Project File?

I need to dynamically add folders into $SUBDIRS , just scan for some folders , and:

for file in plugin_dir
   if folder name ~ "^plugin-[A-Z]+$"
      SUBDIRS += $name
   fi

But how can i implement this in a .pro file ?

We do this by using qmake's system command.

Where we need non-trivial commands to be run, we write a script (we use Python, but any language would do) that we pass info into via command-line options, and that writes out the desired values we want out into a qmake variable.