all : app.exe

clean :
   -@regsvcs /u lib.dll
   -@gacutil /u lib 
   -@del lib.dll
   -@del lib.tlb
   -@del app.exe

app.exe : app.cs lib.dll
   csc /t:winexe app.cs /r:lib.dll

lib.dll : lib.cs
   -@regsvcs /u lib.dll
   csc /t:library lib.cs
   gacutil /i lib.dll
   regsvcs lib.dll