Can I verify signatures without writing files?

[Oscar Levi]

I'm finding that if DATA is a data file and SIG is a detached
signature, I cannot verify the signature without refering to one of
these as a file in the filesystem. 

  gpg --verify sig data			# OK
  cat sig | gpg --verify data		# OK
  cat sig | gpg --verify - data		# OK
  cat sig data | gpg --verify		# Nope
  cat sig data | gpg --verify -		# Nope
  cat sig data | gpg --verify -		# Nope
  cat sig data | gpg --verify -	-	# Nope

Thots?