Re: automated cast to different data type possible?

André Pönitz
2011-05-12T17:13:19Z

On Thursday 12 May 2011 18:05:13 ext Tom Tromey wrote:
> >>>>> "Klaus" == Klaus Rudolph <lts-rudolph@gmx.de> writes:
>
> Tom> You want "set print object on".
>
> Klaus> This only works with classes which includes a vtable, but there
> Klaus> is no virtual function inside that hierarchy.
>
> Sorry about that; you even noted this in your original message and I
> missed it.
>
> Pretty-printers just change how a value is displayed. They don't change
> the type. [...]

Assuming that I understood the task correctly it can be done with
gdb python scripting nevertheless.

Given

struct KRBase
{
enum Type { TYPE_A, TYPE_B } type;
KRBase(Type _type) : type(_type) {}
};

struct KRA : KRBase { int x, y; KRA() : KRBase(TYPE_A), x(1), y(32) {} };
struct KRB : KRBase { KRB() : KRBase(TYPE_B) {} };

void testKR()
{
KRBase *ptr1 = new KRA;
KRBase *ptr2 = new KRB;
break_here();
}

creating a display of

ptr1 @0x809a9d0 KRA
KRBase KRA
x 1 int
y 32 int
ptr2 @0x809a9e0 KRB
KRBase KRB

takes three lines of python code:

def qdump__KRBase(d, item):
base = ["KRA", "KRB"][int(item.value["type"])]
d.putItem(Item(item.value.cast(lookupType(base)), item.iname))

[using, admittedly, the *cough* "other" approach to pretty printing]

Andre'

PS: I put a real screenshot at

http://imageshack.us/photo/my-images/135/kr2e.png

as I am not sure how acceptable attaching a 15k .png is on this list.