Re: Initialization of static anonymous-namespace members from a dynamically loaded lib

From:
Leigh Johnston <leigh@i42.co.uk>
Newsgroups:
comp.lang.c++
Date:
Sun, 09 Jan 2011 21:02:53 +0000
Message-ID:
<J_GdnaKVldv6v7fQnZ2dnUVZ7oednZ2d@giganews.com>
On 09/01/2011 20:56, m0shbear wrote:

Given
// foo.cpp
#include<map>
namespace {
int init_s();
std::map<int,int> m;
int dummy = init_s();
int init_s() {
m[1] = 2;
m[5] = 4;
return 0;
}
};
// ...
int Foo::bar() {
return m[5];
}
// ...

// foo.h
class Foo {
//...
int bar();
// ...
};

If foo.o is linked at build time, the compiler automagically adds the
call to init_s() in the libc++ static init. But if it is dynamically
loaded, this condition is guaranteed to be satisfied. Or is it? I
don't want to waste memory by having an individual copy of supposedly
static data, yet I don't want UB from guessing and hoping.

Is it even possible to have file-scope non-POD statics upon whose
operations do not invoke UB, inside a d-l lib?


Implementation specific behaviour is beyond the scope of this newsgroup;
try a programming newsgroup specific to your platform. The C++ Standard
does not mention dynamically loaded libraries AFAIK.

/Leigh

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