c++ - Unroll loop at compile time -


i want write load of lines c++ file of form foo(i) i = 0,1, ... , n, there way of doing @ compile time?

i want because i've got templated class:

template <int x> class myclass{ ... }

and want test lots of different values of "x" like:

for (int = 0; < n; i++) {     myclass<i> bar;     bar.method()  }

this doesn't work wants value passed template value determined @ compile time.

i write out whole thing:

myclass<0> bar0; bar0.method(); myclass<1> bar1; bar1.method();

and make define speed bit, like:

#define mymacro(x) myclass<x> bar_x; bar_x.method();

but i'd still have write mymacro everywhere , i'm going want change range sensible. if write sort of macro version of loop it'd save me lot of time.

update: needed pass variables method made slight changes accepted answer given @pascal

template<int x> class myclass { public: void foo(int y) { std::cout << x y<< std::endl; } }; template<int x> inline void mytest(int y) { mytest<x - 1>(y); myclass<x-1> bar; bar.foo(y); } template<> inline void mytest<1>(int y) { myclass<0> bar; bar.foo(y); }

a solution closer "macro way" can template recursivity :

template<int x> class myclass { public: void foo() { std::cout << x << std::endl; } }; template<int x> inline void mytest() { mytest<x - 1>(); myclass<x-1> bar; bar.foo(); } template<> inline void mytest<1>() { myclass<0> bar; bar.foo(); } int main() {     mytest<5>();     return 0; }

and output of example :

0 1 2 3 4

Comments

Post a Comment

Popular posts from this blog

Is there a better way to structure post methods in Class Based Views -

i'm using class based views in django , never specify url in ajax calls , omit action parameter in form because know these requests go through post method of class based view. notice view - profile page make many requests depending on user updating on page - post method become convoluted , if/else mess example: def post(self, request, *args, **kwargs): # handle user changing available date if request.post.get('availabledate') != none: self.updateavailabledate(request) return jsonresponse({'result':'success'}) if request.post.get('newprojectname') != none: creative_user = creativeuserprofile.objects.get(id = request.user.id) project = project.create_project(creative_user, request.post['newprojectname']) project.save() return jsonresponse({'projectid': project.id }) if request.post.get('projectimage') != none , request.files['file']: proj...
Read more

performance - Why is XCHG reg, reg a 3 micro-op instruction on modern Intel architectures? -

i'm doing micro-optimization on performance critical part of code , came across sequence of instructions (in at&t syntax): add %rax, %rbx mov %rdx, %rax mov %rbx, %rdx i thought had use case xchg allow me shave instruction , write: add %rbx, %rax xchg %rax, %rdx however, dimay found agner fog's instruction tables , xchg 3 micro-op instruction 2 cycle latency on sandy bridge, ivy bridge, broadwell, haswell , skylake. 3 whole micro-ops , 2 cycles of latency! 3 micro-ops throws off 4-1-1-1 cadence , 2 cycle latency makes worse original in best case since last 2 instructions in original might execute in parallel. now... cpu might breaking instruction micro-ops equivalent to: mov %rax, %tmp mov %rdx, %rax mov %tmp, %rdx where tmp anonymous internal register , suppose last 2 micro-ops run in parallel latency 2 cycles. given register renaming occurs on these micro-architectures, though, doesn't make sense me done way. why wouldn't register renamer ...
Read more

c# - Asp.net web api : redirect unauthorized requst to forbidden page -

im trying redirect unauthorized request forbidden page instead i'm getting forbidden page in response body , how can fix ? here's startup class : app.createperowincontext(storecontext.create); app.createperowincontext<applicationusermanager>(applicationusermanager.create); app.createperowincontext<applicationsigninmanager>(applicationsigninmanager.create); app.usecookieauthentication(new cookieauthenticationoptions { authenticationtype = defaultauthenticationtypes.applicationcookie, expiretimespan = timespan.fromdays(30), }); app.useexternalsignincookie(defaultauthenticationtypes.externalcookie); app.usetwofactorsignincookie(defaultauthenticationtypes.twofactorcookie, timespan.fromminutes(5)); app.usetwofactorrememberbrowsercookie(defaultauthenticationtypes.twofactorrememberbrowsercookie); the method im trying reach : [httpget] [authorize(roles = "admin")] public string getcurrentusername() { return userman...
Read more