[Python-checkins] CVS: python/nondist/peps pep-0214.txt,1.2,1.3

[Barry Warsaw]

Update of /cvsroot/python/python/nondist/peps
In directory slayer.i.sourceforge.net:/tmp/cvs-serv3071

Modified Files:
	pep-0214.txt 
Log Message:
PEP 214 completed after channeling and encouragement from Tim Peters.
The referenced SF patch is current with this description.

The proposal section is moved to before the justification.


Index: pep-0214.txt
===================================================================
RCS file: /cvsroot/python/python/nondist/peps/pep-0214.txt,v
retrieving revision 1.2
retrieving revision 1.3
diff -C2 -r1.2 -r1.3
*** pep-0214.txt	2000/08/15 22:45:06	1.2
--- pep-0214.txt	2000/08/16 14:59:57	1.3
***************
*** 3,10 ****
  Version: $Revision$
  Author: bwarsaw@beopen.com (Barry A. Warsaw)
! Python-Version: 2.1
  Status: Draft
  Created: 24-Jul-2000
! Post-History:
  
  
--- 3,10 ----
  Version: $Revision$
  Author: bwarsaw@beopen.com (Barry A. Warsaw)
! Python-Version: 2.0
  Status: Draft
  Created: 24-Jul-2000
! Post-History: 16-Aug-2000
  
  
***************
*** 22,25 ****
--- 22,56 ----
  
  
+ Proposal
+ 
+     This proposal introduces a syntax extension to the print
+     statement, which allows the programmer to optionally specify the
+     output file target.  An example usage is as follows:
+ 
+         print >> mylogfile, 'this message goes to my log file'
+ 
+     Formally, the syntax of the extended print statement is
+     
+         print_stmt: ... | '>>' test [ (',' test)+ [','] ] )
+ 
+     where the ellipsis indicates the original print_stmt syntax
+     unchanged.  In the extended form, the expression just after >>
+     must yield an object with a write() method (i.e. a file-like
+     object).  Thus these two statements are equivalent:
+ 
+ 	print 'hello world'
+         print >> sys.stdout, 'hello world'
+ 
+     As are these two statements:
+ 
+         print
+         print >> sys.stdout
+ 
+     These two statements are syntax errors:
+ 
+         print ,
+         print >> sys.stdout,
+ 
+ 
  Justification
  
***************
*** 41,50 ****
      than specifically standard output.  A typical idiom is
  
- 	oldstdout = sys.stdout
          sys.stdout = mylogfile
  	try:
  	    print 'this message goes to my log file'
  	finally:
! 	    sys.stdout = oldstdout
  
      The problem with this approach is that the binding is global, and
--- 72,80 ----
      than specifically standard output.  A typical idiom is
  
          sys.stdout = mylogfile
  	try:
  	    print 'this message goes to my log file'
  	finally:
! 	    sys.stdout = sys.__stdout__
  
      The problem with this approach is that the binding is global, and
***************
*** 54,105 ****
  
      This approach is also very inconvenient for interleaving prints to
!     various output streams.
! 
! 
! Proposal
  
-     This proposal introduces a syntax change to the print statement,
-     which allows the programmer to optionally specify the output file
-     target.  An example usage is as follows:
- 
-         print >> mylogfile, 'this message goes to my log file'
- 
-     Formally, the syntax of the extended print statement is
- 
-         print_stmt: "print" [">>" expr ","] [ expr ("," expr)* [","] ]
- 
-     Where the the expression just after >> must yield an object with a
-     write() method (i.e. a file-like object).  Thus these two
-     statements are equivalent:
- 
- 	print 'hello world'
-         print >> sys.stdout, 'hello world'
- 
- 
- Open Issues
- 
-     What should the following do?
- 
-         print >> file
-         print >> file,
- 
-     In the current implementation (see below), the first is a
-     SyntaxError and the second prints nothing to file.  This is likely
-     counterintuitive; the first should print just a newline, making
-     these equivalent:
- 
-         print >> sys.stdout
-         print
- 
-     The second should print just a space and no newline to file.  It
-     doesn't have a non-extended print equivalent, since this is
-     illegal:
- 
-         print ,
- 
-     The closes equivalent is:
- 
-         print '',
-     
  
  Reference Implementation
--- 84,90 ----
  
      This approach is also very inconvenient for interleaving prints to
!     various output streams, and complicates coding in the face of
!     legitimate try/except or try/finally clauses.
  
  
  Reference Implementation