Hi,
Initialiation ordering: Function-local static objects (previously
described) are the easiest solution, but the lifetime of such objects is
undefined, i.e. their destruction time is unspecified, sometimes *never*
destroyed. (Related to the halting problem: when will a program
terminate or when is the last time a particular object will be
referenced?) Fortunately, for most programs destruction ordering at
exit-time is moot, the program's memory is released anyways, so who
cares(?).
Initialization missing(!): With the Mach lazy linker, an entire
module (.o) may not even be linked into the final executable at link-time
if the linker thinks a module will not be used -- this leads to missing
modules (and their static objects) at run time. In my experience, the
linker has thought wrong on many accounts (not a bug), so to coerce
linkage, I will insert a line of code somewhere that certainly uses a
symbol in the module in question, such as a non-inline Object::Object()
constructor. This then triggers linkage of that module at link time.
(Results evident from change in resulting binary's size!) Note that link
*ordering* is still undefined.
If you have an entire hierarchy of static object
initialization-ordering dependencies, you can use the function-local
static technique repeatedly with "requires-provides" relationships to make
sure dependencies are met. Perhaps somewhat painful, sometimes necessary.
Hope this sheds some light.
> > I am facing one strange problem, in which i am not able to
> > get static object initialized completely or properly before
> > its use, and hence it is giving unexpected results.
> >
> > Is there any compile time option to force such initialization?
> > Or is there any other issue which creates such problems?
>
> Initialize the object inside a function. Then it will always be
> initialized before it's used. The order in which global static
> objects are initialized isn't reliable, but objects in a function are
> always initialized before the function is called.
>
> Object& getObject() {
> static Object object;
> return object;
> }
David Fang
Computer Systems Laboratory
Electrical & Computer Engineering
Cornell University
http://www.csl.cornell.edu/~fang/
-- (2400 baud? Netscape 3.0?? lynx??? No problem!)
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