Hi,

When designing the string classes in the standard library was an
immutable string class considered.

The rational for this is that the aquistion and release of mutext locks,
in a multi threaded program,  on the standard string class are not necessary
when a string is created that will never be modified.

Obviously only a subset of the member fuctions of the standard string class
would be avaiable on such a class.


David Hunter

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In article <7c8fgc$t96$1@nnrp1.dejanews.com>, dhunter@lehman.com wrote:

> Hi,
>
> When designing the string classes in the standard library was an
> immutable string class considered.
>
> The rational for this is that the aquistion and release of mutext locks,
> in a multi threaded program,  on the standard string class are not necessary
> when a string is created that will never be modified.
>
> Obviously only a subset of the member fuctions of the standard string class
> would be avaiable on such a class.

Yes, it's called const string.  However if you make a const copy of the
const string, you must still protect the refcount in the destructor** so
that the threads can agree who will delete the data.

**Footnote: Or otherwise assure that the decrement and test operation on
the refcount is atomic.

-Howard


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