[Python-checkins] CVS: python/nondist/peps pep-0247.txt,1.7,1.8

[A.M. Kuchling]

Update of /cvsroot/python/python/nondist/peps
In directory usw-pr-cvs1:/tmp/cvs-serv2895

Modified Files:
	pep-0247.txt 
Log Message:
Add rationale section


Index: pep-0247.txt
===================================================================
RCS file: /cvsroot/python/python/nondist/peps/pep-0247.txt,v
retrieving revision 1.7
retrieving revision 1.8
diff -C2 -d -r1.7 -r1.8
*** pep-0247.txt	2001/10/09 21:13:07	1.7
--- pep-0247.txt	2001/10/22 02:10:29	1.8
***************
*** 116,119 ****
--- 116,137 ----
  
  
+ Rationale
+ 
+     The digest size is measured in bytes, not bits, even though hash
+     algorithm sizes are usually quoted in bits; MD5 is a 128-bit
+     algorithm and not a 16-byte one, for example.  This is because, in
+     the sample code I looked at, the length in bytes is often needed
+     (to seek ahead or behind in a file; to compute the length of an
+     output string) while the length in bits is rarely used.
+     Therefore, the burden will fall on the few people actually needing
+     the size in bits, who will have to multiply digest_size by 8.
+ 
+     It's been suggested that the update() method would be better named
+     append().  However, that method is really causing the current
+     state of the hashing object to be updated, and update() is already
+     used by the md5 and sha modules included with Python, so it seems
+     simplest to leave the name update() alone.
+ 
+ 
  Changes