Subject: [Boost-commit] svn:boost r65551 - sandbox/variadic_templates/libs/composite_storage/sandbox/pack
From: cppljevans_at_[hidden]
Date: 2010-09-23 11:46:59
Author: cppljevans
Date: 2010-09-23 11:46:58 EDT (Thu, 23 Sep 2010)
New Revision: 65551
URL: http://svn.boost.org/trac/boost/changeset/65551
Log:
demo same size as ebo for inherited components
Added:
sandbox/variadic_templates/libs/composite_storage/sandbox/pack/empty_base.cpp (contents, props changed)
Added: sandbox/variadic_templates/libs/composite_storage/sandbox/pack/empty_base.cpp
==============================================================================
--- (empty file)
+++ sandbox/variadic_templates/libs/composite_storage/sandbox/pack/empty_base.cpp 2010-09-23 11:46:58 EDT (Thu, 23 Sep 2010)
@@ -0,0 +1,87 @@
+//Purpose:
+// See if more than 1 empty base types contribute
+// more to size of derived type than just 1
+// empty_base type.
+//Result:
+// No. Output is:
+// sizeof(empty_class<0>)=1
+// sizeof(empties_inherits)=1
+// sizeof(empties_member)=2
+// sizeof(empties_all_of)=1
+//
+#include <boost/composite_storage/pack/container_all_of_aligned.hpp>
+#include <iostream>
+
+ template
+ < unsigned I
+ >
+struct empty_class
+{
+ friend
+ std::ostream&
+ operator<<
+ ( std::ostream& sout
+ , empty_class<I>const&
+ )
+ {
+ sout<<"empty_class<"<<I<<">const&";
+ return sout;
+ }
+ unsigned
+ get(void)const
+ {
+ return I;
+ }
+ #if 0
+ unsigned my_i;
+ empty_class(void):my_i(I){}
+ #endif
+};
+
+struct empties_inherit
+: empty_class<0>
+, empty_class<1>
+{};
+
+struct empties_member
+{
+ empty_class<0> m0;
+ empty_class<1> m1;
+};
+ typedef
+ boost::composite_storage::pack::container
+ < boost::composite_storage::tags::all_of_aligned
+ , boost::mpl::integral_c<unsigned,0>
+ , empty_class<0>
+ , empty_class<1>
+ >
+empties_all_of
+;
+int main(void)
+{
+ std::cout<<"sizeof(empty_class<0>)="<<sizeof(empty_class<0>)<<"\n";
+ std::cout<<"sizeof(empties_inherit)="<<sizeof(empties_inherit)<<"\n";
+ std::cout<<"sizeof(empties_member)="<<sizeof(empties_member)<<"\n";
+ std::cout<<"sizeof(empties_all_of)="<<sizeof(empties_all_of)<<"\n";
+ {
+ empties_inherit ei_v;
+ empty_class<0>*p0=&ei_v;
+ empty_class<1>*p1=&ei_v;
+ std::cout<<"p0="<<p0<<"\n";
+ std::cout<<"p1="<<p1<<"\n";
+ std::cout<<"*p0="<<*p0<<"\n";
+ std::cout<<"*p1="<<*p1<<"\n";
+ }
+ {
+ empties_all_of ea_v;
+ empty_class<0>&r0=ea_v.project<0>();
+ empty_class<1>&r1=ea_v.project<1>();
+ std::cout<<"r0="<<r0<<"\n";
+ std::cout<<"r1="<<r1<<"\n";
+ std::cout<<"&ea_v="<<&ea_v<<"\n";
+ std::cout<<"&r0="<<&r0<<"\n";
+ std::cout<<"&r1="<<&r1<<"\n";
+ std::cout<<"r1.get()="<<r1.get()<<"\n";
+ }
+ return 0;
+}