Rance Hall wrote:
Ok so I know what I am doing is deprecated (or at least poor form) but
the replacement must be awkward cause I'm not getting it.
[...]
message = "Bah."
if test:
message = message + " Humbug!"
It's not deprecated, nor is it poor form. However, it can be abused, or
perhaps *misused* is a better term, and it is the misuse you need to
watch out for.
Somebody posted a similar comment on another Python list today, which I
answered, so I'll copy and paste my answer here:
There's nothing wrong with concatenating (say) two or three strings.
What's a bad idea is something like:
s = ''
while condition:
s += "append stuff to end"
Even worse:
s = ''
while condition:
s = "insert stuff at beginning" + s
because that defeats the runtime optimization (CPython only!) that
*sometimes* can alleviate the badness of repeated string concatenation.
See Joel on Software for more:
http://www.joelonsoftware.com/articles/fog0000000319.html
But a single concatenation is more or less equally efficient as string
formatting operations (and probably more efficient, because you don't
have the overheard of parsing the format mini-language).
For repeated concatenation, the usual idiom is to collect all the
substrings in a list, then join them all at once at the end:
pieces = []
while condition:
pieces.append('append stuff at end')
s = ''.join(pieces)
--
Steven
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