example of <list> with auto_buffer ?

Would anyone have a short example or two of <list> s with auto_buffer, i.e. "STLSoft for dummies" ? I'm looking at somebody else's code with <list>, just want to speed it up. Thanks, cheers -- denis

Hi Denis I'm a bit unclear what you want to achieve. Can you maybe provide a bit of pseudo-code to illustrate your point? Cheers Matt "Denis" <denis-bz-py@t-online.de> wrote in message news:h4n2of$2n75$1@digitalmars.com... > Would anyone have a short example or two of <list> s with auto_buffer, > i.e. "STLSoft for dummies" ? I'm looking at somebody else's code with <list>, > just want to speed it up. > Thanks, > cheers > -- denis

Matthew Wilson Wrote: > Hi Denis > > I'm a bit unclear what you want to achieve. Can you maybe provide a bit of pseudo-code to illustrate your point ? Right; how do I do the below ? I thought buffer_t would be an allocator, wrong -- // vector on stack, stlsoft::auto_buffer ? #include <stlsoft/memory/auto_buffer.hpp> #include <vector> using namespace std; int main( int argc, char* argv[] ) { typedef stlsoft::auto_buffer<int, 64> buffer_t; vector<int, buffer_t> v; // <-- faster vector<int> ? wrong int n = (argv[1] ? atoi( argv[1] ) : 10000000); while( --n >= 0 ){ v.push_back( 0 ); v.pop_back(); } }

Ah, I see This is accounted for by using the pod_vector class template, as in: #include <stlsoft/containers/pod_vector.hpp> stlsoft::pod_vector<int, std::allocator<int>, 64> v; HTH Matt "Denis" <denis-bz-py@t-online.de> wrote in message news:h4udcv$1vvi$1@digitalmars.com... > Matthew Wilson Wrote: > > > Hi Denis > > > > I'm a bit unclear what you want to achieve. Can you maybe provide a bit of pseudo-code to illustrate your point ? > > Right; how do I do the below ? I thought buffer_t would be an allocator, wrong -- > > // vector on stack, stlsoft::auto_buffer ? > #include <stlsoft/memory/auto_buffer.hpp> > #include <vector> > using namespace std; > > int main( int argc, char* argv[] ) > { > typedef stlsoft::auto_buffer<int, 64> buffer_t; > > vector<int, buffer_t> v; // <-- faster vector<int> ? wrong > > int n = (argv[1] ? atoi( argv[1] ) : 10000000); > while( --n >= 0 ){ > v.push_back( 0 ); > v.pop_back(); > } > } >

Thanks Matt, what I really want is vector<int> / stack<int> faster than stl; thought naively that stack allocation would be fast (for macs, gcc -- I have no idea if apple have optimized stl at all.) What would you suggest ? Thanks, cheers -- denis

Denis Wrote: > Thanks Matt, > what I really want is vector<int> / stack<int> faster than stl; > thought naively that stack allocation would be fast stlsoft::pod_vector<int> is effectively vector<int> using stack In certain circumstances it is faster. See section 32.2.8 of Imperfect C++ > (for macs, gcc -- I have no idea if apple have optimized stl at all.) > What would you suggest ? Without further detail on your requirements, I'd suggest pod_vector. > Thanks, cheers > -- denis >

Matt, what I'm looking for is fast <vector> push / pop / [] but stlsoft is quite a bit slower -- * 4 ns int[10], fixed size on the stack * 40 ns <vector> * 1300 ns <stlsoft/containers/pod_vector.hpp> for the stupid test below -- just 2 push, v[0] v[1], 2 pop, on one platform, mac ppc, only; your mileage will vary. Nonetheless factors > 2 surprise me. ("The purpose of computing is insight, not numbers" -- but for timing, you need numbers.) #include <stlsoft/containers/pod_vector.hpp> #include <stdio.h> using namespace std; int main( int argc, char* argv[] ) { // times for 2 push, v[0] v[1], 2 pop, mac g4 ppc gcc-4.2 -O3 -- // Vecint10 v; // stack int[10]: 4 ns vector<int> v; // 40 ns // stlsoft::pod_vector<int> v; // 1300 ns // stlsoft::pod_vector<int, std::allocator<int>, 64> v; int n = (argv[1] ? atoi( argv[1] ) : 10) * 1000000; int sum = 0; while( --n >= 0 ){ v.push_back( n ); v.push_back( n ); sum += v[0] + v[1]; v.pop_back(); v.pop_back(); } printf( "sum: %d\n", sum ); }