[Lazarus] Library function trashing object

[Lubos Pintes]

Yet another thing, someone also mentioned this.
The cdecl calling convention corresponds to extern "C" in C++. Maybe you 
are using stdcall in your C++ library?
Or perhaps you are on Linux where this is not relevant? But the extern 
"C" could be relevant also on Linux.

Dňa 19. 4. 2013 21:24 Lubos Pintes wrote / napísal(a):
> This is How I understand the var parameter.
> It is an address, but is treated as normal variable, so it is not 
> needed to dereference a pointer.
> For example
> int f(int* x) in C/C++ corresponds to
> function f(var x: integer): integer;
> Now we have
> int f(int x);
> If you declare it as
> function f(var x: integer): integer;
> and then try to assign something to x, the access violation is very 
> probably raised because x contains value, not address.
> Dňa 19. 4. 2013 21:15 Leonardo M. Ramé wrote / napísal(a):
>> On 2013-04-19 21:08:29 +0200, Lubos Pintes wrote:
>>> I probably don't understand. You will be able to change it, I see no
>>> problem. It is a local variable which can be changed.
>>>
>>> Dňa 19. 4. 2013 20:55 Leonardo M. Ramé wrote / napísal(a):
>>>> On 2013-04-19 20:52:04 +0200, Lubos Pintes wrote:
>>>>> I think you could not declare the second parameter of GetData as var
>>>>> parameter. Because it is then treated as address.
>>>>> I am not sure what corresponds to C++ unsigned long, perhaps 
>>>>> LongWord?
>>>>> So try to change the second parameter so that it is not a var 
>>>>> parameter.
>>>>> Dňa 19. 4. 2013 19:18 Leonardo M. Ramé wrote / napísal(a):
>>>> But I need the 2nd param to be changed by the function, that's why I
>>>> declare it as var.
>>>>
>> Well, removing the "var" in the 2nd param, at least allowed avoid the
>> SIGSEGV. I don't know why, though.
>>
>