[odb-users] Delayed initialization of polymorphic_entry_for_X and create_schema_entry_

[Boris Kolpackov]

Hi Steffen,

steffen at boast.nl <steffen at boast.nl> writes:

> I ran into a problem which I think is related to delayed
> initialization of the variable polymorphic_entry_for_X.
> 
> I have a polymorphic object structure that is peristed to ODB, say A
> : B. I now try to read all objects using database.query<B>().
> Entities are stored using perist(QSharedPointer<B>); Thus, odb is
> never (compile time) made aware of the existence of type A in this
> case. I have two applications with the same code; one works, one
> throws a "no type information" exception?
> 
> By adding a reading database.query<A>() to the code, it works in
> both applications. As the code is shared between the two
> application, the only cause I can think of is a delayed
> initialization of polymorphic_entry_for_A. Is that correct?

The only situation where you can have delayed static global (as opposed to
function-local) object initialization is if you delay loading the shared
library that contains it. I've never heard of delayed initialization of
objects that are already loaded into the process' memory. Maybe with
RTLD_LAZY? Or, perhaps, you are using a static library and since nobody
references A, the corresponding object file doesn't get linked. I think
this must be it.

What exactly is your setup (i.e., is A in a static/shared library and if
so how is it loaded) and platform?

Boris