On 02 Apr 2011, at 18:19, Jürgen Hestermann wrote: > >> I would never expect an assignmet to nil changing anything else than just > >> the value of the pointer. And for (all?) other pointers this expectation > >> is valid. > > That expectation is not valid for any reference counted type (be it a > > dynamic array, ansistring, unicodestring, COM-style interfaces). That's the > > whole point of reference counted types: they keep track of how many > > references still exist to the data, and once that reaches zero the data is > > freed. > > But I just assign a value to a pointer,
No, you assign a value to a dynamic array. A dynamic array is not a plain pointer, just like a COM-style interface is not a plain pointer. Assigning nil to a COM-style interface does not set its value simply to nil either. There is also no difference between assigning the constant nil to a dynamic array variable and assigning a dynamic array with length 0 to a dynamic array variable (since empty arrays are also represented by a nil pointer, even if they are stored inside a variable). > > The correct way to do so is to call initialize() on the field. > > It's not mentioned in the documentation you refered to > (http://www.freepascal.org/docs-html/ref/refsu15.html#x39-450003.3.1). The documentation for the initialize routine indeed seems to be missing. > And I don't need any other routine because fillchar does the job. Fillchar does the job just like adding inline assembler would do the job. It's a hack. > The irritation just was, that I expected an assignment to nil doing exactly > the same as fillchar(..,#0). And I am still astonished that it does more. > What other traps are lurking under the hood? It's hard to program if you have > to fight with undocumented "features" instead of concentrating on my own > mistakes... If you don't want the compiler to interfere with anything you do, do not use automated types such as ansistring, unicodestring, dynamic array and COM-style interfaces. The whole point of these types is that the compiler will do lots of stuff behind your back, because without that the reference counting cannot work. Jonas_______________________________________________ fpc-pascal maillist - fpc-pascal@lists.freepascal.org http://lists.freepascal.org/mailman/listinfo/fpc-pascal
