[arch-general] Set BUILDDIR in makepkg.conf

Hey, guys, is there a way to set BUILDDIR in makepkg.conf to a place like /var/abs/mybuilds/$pkgname? I tried set BUILDDIR="/var/abs/mybuilds/$pkgname",but it didn't work,it builds in /var/abs/mybuilds,not in /var/abs/mybuilds/$pkgname.