Home Original page

How can you copy (clone) a string?

Joal Heagney s713221 at student.gu.edu.au
Fri Oct 6 04:13:50 EDT 2000 
Greg Ewing wrote:

> Joal Heagney wrote:
> >
> > However, I don't understand it
> > all, because when you just create the strings as follows:
> > >>> a = 'aa'
> > >>> b = 'aa'
> > >>> c = 'aa'
> > >>> d = 'aa'
> > >>> id(a), id(b), id(c), id(d)
> > (134879088, 134879088, 134879088, 134879088)
>
> In the interests of speed, the strings used internally
> to hold the names of variables, attributes, etc. are
> "interned" (i.e. stored uniquely in a table). The compiler
> also does this to string constants that you write into
> your code, such as 'aa' above, in some cases, both to
> save space, and just in case you want to use one
> in a getattr call or something like that.
>
> However, this is not done for strings that you compute
> at runtime in some way. That would take a lot of time
> for hardly any benefit, since it's extremely rare to
> use a computed string as a variable name.
>
> --
> Greg Ewing, Computer Science Dept, University of Canterbury,
> Christchurch, New Zealand
> To get my email address, please visit my web page:
> http://www.cosc.canterbury.ac.nz/~greg

Thank you for your explanation. I assume 2*'a' is an example of a
runtime computed string?

Joal Heagney/AncientHart
More information about the Python-list mailing list