Am 07.07.2011 08:35, schrieb Alexander Klenin: >> As further support for #1, consider: With a class, you do not have to pass >> it to a procedure as var, but when you modify the instance, you modify the >> same instance as was passed to the procedure. That is how classes work. >> Having a variable point to the same object as another variable does in fact >> mean it's the same instance, the same object. That is Object Pascal's object >> model. But with strings, if you want to modify the string in a procedure and >> have that affect the argument initially passed to the procedure you *have* >> to use var. That alone should be convincing evidence that the programmer is >> always supposed to be able to assume that unique variables are unique >> instances for automatically managed strings and arrays. > This is also a good argument which I omitted before in the interests of > brevity. > > Put in another words, current "const string" implementation honors the > implicit contract of > "adding const in front of the string parameter cancels refcounting", > at the cost of breaking the implicit contract of "refcounted values > are indistinguishable > from simple values (except maybe in performance)".
As I have shown before in this thread, non ref. counted values e.g. shortstrings are affected by the same problem. _______________________________________________ fpc-devel maillist - fpc-devel@lists.freepascal.org http://lists.freepascal.org/mailman/listinfo/fpc-devel
