[Python-checkins] CVS: python/nondist/peps pep-0234.txt,1.10,1.11

[Guido van Rossum]

Update of /cvsroot/python/python/nondist/peps
In directory usw-pr-cvs1:/tmp/cvs-serv2159

Modified Files:
	pep-0234.txt 
Log Message:
Correct typos and add bits of discussion.  Also add another "chief
virtue".


Index: pep-0234.txt
===================================================================
RCS file: /cvsroot/python/python/nondist/peps/pep-0234.txt,v
retrieving revision 1.10
retrieving revision 1.11
diff -C2 -r1.10 -r1.11
*** pep-0234.txt	2001/05/01 02:29:03	1.10
--- pep-0234.txt	2001/05/01 11:42:07	1.11
***************
*** 20,24 ****
      In addition, specific iterators over the keys of a dictionary and
      over the lines of a file are proposed, and a proposal is made to
!     allow spelling dict.kas_key(key) as "key in dict".
  
      Note: this is an almost complete rewrite of this PEP by the second
--- 20,24 ----
      In addition, specific iterators over the keys of a dictionary and
      over the lines of a file are proposed, and a proposal is made to
!     allow spelling dict.has_key(key) as "key in dict".
  
      Note: this is an almost complete rewrite of this PEP by the second
***************
*** 117,128 ****
        next value from the iterator.  If the callable raises an
        exception, this is propagated normally; in particular, the
!       function is allowed to raise StopError as an alternative way to
!       end the iteration.  (This functionality is available from the C
!       API as PyCallIter_New(callable, sentinel).)
  
      Iterator objects returned by either form of iter() have a next()
      method.  This method either returns the next value in the
!     iteration, or raises StopError (or a derived exception class) to
!     signal the end of the iteration.  Any other exception should be
      considered to signify an error and should be propagated normally,
      not taken to mean the end of the iteration.
--- 117,128 ----
        next value from the iterator.  If the callable raises an
        exception, this is propagated normally; in particular, the
!       function is allowed to raise StopIteration as an alternative way
!       to end the iteration.  (This functionality is available from the
!       C API as PyCallIter_New(callable, sentinel).)
  
      Iterator objects returned by either form of iter() have a next()
      method.  This method either returns the next value in the
!     iteration, or raises StopIteration (or a derived exception class)
!     to signal the end of the iteration.  Any other exception should be
      considered to signify an error and should be propagated normally,
      not taken to mean the end of the iteration.
***************
*** 213,221 ****
      If all the parts of the proposal are included, this addresses many
      concerns in a consistent and flexible fashion.  Among its chief
!     virtues are the following three -- no, four -- no, five -- points:
  
      1. It provides an extensible iterator interface.
  
!     1. It allows performance enhancements to list iteration.
  
      3. It allows big performance enhancements to dictionary iteration.
--- 213,221 ----
      If all the parts of the proposal are included, this addresses many
      concerns in a consistent and flexible fashion.  Among its chief
!     virtues are the following four -- no, five -- no, six -- points:
  
      1. It provides an extensible iterator interface.
  
!     2. It allows performance enhancements to list iteration.
  
      3. It allows big performance enhancements to dictionary iteration.
***************
*** 229,233 ****
--- 229,236 ----
         {__getitem__, keys, values, items}.
  
+     6. It makes code iterating over non-sequence collections more
+        concise and readable.
  
+ 
  Open Issues
  
***************
*** 235,244 ****
  
      - The name iter() is an abbreviation.  Alternatives proposed
!       include iterate(), harp(), traverse(), narrate().
  
      - Using the same name for two different operations (getting an
        iterator from an object and making an iterator for a function
        with an sentinel value) is somewhat ugly.  I haven't seen a
!       better name for the second operation though.
  
      - Once a particular iterator object has raised StopIteration, will
--- 238,250 ----
  
      - The name iter() is an abbreviation.  Alternatives proposed
!       include iterate(), traverse(), but these appear too long.
!       Python has a history of using abbrs for common builtins,
!       e.g. repr(), str(), len().
  
      - Using the same name for two different operations (getting an
        iterator from an object and making an iterator for a function
        with an sentinel value) is somewhat ugly.  I haven't seen a
!       better name for the second operation though, and since they both
!       return an iterator, it's easy to remember.
  
      - Once a particular iterator object has raised StopIteration, will
***************
*** 287,292 ****
        dict" and "if x in dict" too compelling to break, and there's not
        much overhead in having to write dict[x] to explicitly get the
!       value.  We could also add methods to dictionaries that return
!       different kinds of iterators, e.g.
  
            for key, value in dict.iteritems(): ...
--- 293,308 ----
        dict" and "if x in dict" too compelling to break, and there's not
        much overhead in having to write dict[x] to explicitly get the
!       value.  I've also timed the difference between
! 
!           for key in dict: dict[key]
! 
!       and
! 
!           for key, value in dict[key]: pass
! 
!       and found that these run at about the same speed.
! 
!       We could also add methods to dictionaries that return different
!       kinds of iterators, e.g.
  
            for key, value in dict.iteritems(): ...