changing !define APPNAME "myapp" with script

Hello,

I've been using nsis for my installers, however i need many duplicates of the same installer which will have different APPNAME. can I chagne the APPNAME from the script, i was planning to read the exe name and make it the appname.

also is it possible to write

CreateShortCut "$DESKTOP\" & APPNAME & ".lnk" "$INSTDIR\MyApp.exe"

where appname is variable.

Thanks

!define APPNAME "MyApp"
...
CreateShortCut "$DESKTOP\${APPNAME}.lnk" "$INSTDIR\MyApp.exe"

Stu