[Patches] [ python-Patches-976162 ] Deferred String Addtion: Proof-of-concept

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Patches item #976162, was opened at 2004-06-20 05:10
Message generated for change (Comment added) made by rhettinger
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Category: Library (Lib)
Group: None
Status: Open
Resolution: None
Priority: 1
Submitted By: Raymond Hettinger (rhettinger)
Assigned to: Nobody/Anonymous (nobody)
Summary: Deferred String Addtion:  Proof-of-concept

Initial Comment:
The attached patch demonstrats a possible
implementation for 
deferred string addition.  The idea is to have
str.__add__ save references to its inputs rather that
do the concatenation immediately.  The moment some
other method needs the full string, it is generated
recursively so that the whole concatenation can be done
with a single join.



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>Comment By: Raymond Hettinger (rhettinger)
Date: 2004-06-21 23:28

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The patch is not meant to be loaded to UserString.  Rather
it is a proof-of-concept demonstration of how deferred
string addition would work. Even it pure python form, it
shows how to convert an O(n**2) process to O(n).  If the
concept is approved, the goal is to alter the C code for
stringobject.c, unicodeobject.c, and to make a more thorough
version for UserString.

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Comment By: Jim Jewett (jimjjewett)
Date: 2004-06-21 09:31

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There is an implicit assumption that any component/part with 
its own 'components' attribute will be another UserString (or, 
at the very least, will act like one when traversed).

Would it be better to check whether the subobject actually is 
a UserString (since new-style objects can freely use multiple 
inheritance), or to do some sort of guard in add?  (Perhaps 
immediately stringifying anything with a components attribute 
that is not a UserString?)


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