[Python-checkins] r47199 - sandbox/trunk/Doc/functional.rst

[andrew.kuchling]

Author: andrew.kuchling
Date: Sun Jul  2 22:02:24 2006
New Revision: 47199

Modified:
   sandbox/trunk/Doc/functional.rst
Log:
Correct explanation of 'if' clauses in listcomps; untabify

Modified: sandbox/trunk/Doc/functional.rst
==============================================================================
--- sandbox/trunk/Doc/functional.rst	(original)
+++ sandbox/trunk/Doc/functional.rst	Sun Jul  2 22:02:24 2006
@@ -1,7 +1,7 @@
 Functional Programming HOWTO
 ================================
 
-**Version 0.11**
+**Version 0.12**
 
 (This is a first draft.  Please send comments/error
 reports/suggestions to amk at amk.ca.  This URL is probably not going to
@@ -373,14 +373,17 @@
 List comprehensions have the form::
 
     [ expression for expr in sequence1 
+                 if condition1
                  for expr2 in sequence2
+                 if condition2
                  for expr3 in sequence3 ...
+                 if condition3
                  for exprN in sequenceN
-                 if condition ]
+                 if conditionN ]
 
 The elements of the generated list will be the successive
-values of ``expression``.  The final ``if`` clause is
-optional; if present, ``expression`` is only evaluated and added to
+values of ``expression``.  The ``if`` clauses are
+all optional; if present, ``expression`` is only evaluated and added to
 the result when ``condition`` is true.
 
 The ``for...in`` clauses contain the sequences to be iterated over.
@@ -394,13 +397,18 @@
 Python code::
 
     for expr1 in sequence1:
+        if not (condition1):
+            continue
         for expr2 in sequence2:
-        ...
+            if not (condition2):
+                continue
+            ...
             for exprN in sequenceN:
-                 if (condition):
-                      # Append the value of 
-                      # the expression to the 
-                      # resulting list.
+                 if not (conditionN):
+                     continue
+                 # Append the value of 
+                 # the expression to the 
+                 # resulting list.
 
 This means that when there are multiple ``for...in``
 clauses, the resulting list will be equal to the product of the
@@ -444,7 +452,7 @@
 count, so if you want to create an iterator that will be immediately
 passed to a function you could write::
 
-	obj_total = sum(obj.count for obj in list_all_objects())
+        obj_total = sum(obj.count for obj in list_all_objects())
 
 
 Generators
@@ -782,7 +790,7 @@
       [9878, 9828, 8442, 7953, 6431, 6213, 2207, 769]
 
 (For a more detailed discussion of sorting, see the Sorting mini-HOWTO
-in the Python wiki at http://wiki.python.org/moin/SortingHowto.)
+in the Python wiki at http://wiki.python.org/moin/HowTo/Sorting.)
 
 The ``any(iter)`` and ``all(iter)`` built-ins look at 
 the truth values of an iterable's contents.  ``any()`` returns 
@@ -857,7 +865,7 @@
 ``def`` statements makes things a little bit better::
 
     def combine (a, b):
-	return 0, a[1] + b[1]
+        return 0, a[1] + b[1]
 
     return reduce(combine, items)[1]
 
@@ -1133,7 +1141,8 @@
 
 The author would like to thank the following people for offering
 suggestions, corrections and assistance with various drafts of this
-article: Ian Bicking, Raymond Hettinger, Jim Jewett, Leandro Lameiro.
+article: Ian Bicking, Nick Coghlan, Raymond Hettinger, Jim Jewett,
+Leandro Lameiro.
 
 Version 0.1: posted June 30 2006.