[Python-Dev] PATCH submitted: Speed up + for string concatenation, now as fast as "".join(x) idiom
jcarlson at uci.edu
Thu Oct 5 22:05:09 CEST 2006
"Gregory P. Smith" <greg at electricrain.com> wrote:
> > I've never liked the "".join() idiom for string concatenation; in my
> > opinion it violates the principles "Beautiful is better than ugly." and
> > "There should be one-- and preferably only one --obvious way to do it.".
> > (And perhaps several others.) To that end I've submitted patch #1569040
> > to SourceForge:
> > http://sourceforge.net/tracker/index.php?func=detail&aid=1569040&group_id=5470&atid=305470
> > This patch speeds up using + for string concatenation.
> yay! i'm glad to see this. i hate the "".join syntax. i still write
> that as string.join() because thats at least readable). it also fixes
> the python idiom for fast string concatenation as intended; anyone
> whos ever written code that builds a large string value by pushing
> substrings into a list only to call join later should agree.
> mystr = "prefix"
> while bla:
> mystr += moredata
Regardless of "nicer to read", I would just point out that Guido has
stated that Python will not have strings implemented as trees. Also,
Python 3.x will have a data type called 'bytes', which will be the
default return of file.read() (when files are opened as binary), which
uses an over-allocation strategy like lists to get relatively fast
concatenation (on the order of lst1 += lst2).
More information about the Python-Dev