c++ - Do the new C++11 emplace methods make the previous C++98/03 push_back/insert methods obsolete? -


this question has answer here:

does still make sense in c++11 use vector::push_back() instead of vector::emplace_back(), , map::insert() instead of map::emplace()?

my understanding new modern c++11 emplace-methods construct objects in place given arguments (perfectly forwarded constructors), save copy , move operations, should more efficient old c++98/03 counterparts.

am missing that?

is safe discourage use of old-style methods?

as say, emplace_back meant construct objects. if have object , want copy or move inside container? why should call emplace_back create new instance, if can move existing object new instance?

both alternatives can useful, different purposes. emplace_back might able same push_back same performance, it's still cleaner show intent in code.


Comments

Post a Comment

Popular posts from this blog

apache - Remove .php and add trailing slash in url using htaccess not loading css -

i have add following code htaccess file removing .php extension , add trailing slash urls. worked fine reduced page loading speed , css code not loading @ all. pages ugly. please help rewriteengine on rewritebase / ## hide .php extension snippet # externally redirect /dir/foo.php /dir/foo rewritecond %{the_request} ^[a-z]{3,}\s([^.]+)\.php [nc] rewriterule ^ %1/ [r,l] # add trailing slash rewritecond %{request_filename} !-f rewritecond %{request_uri} !/$ rewriterule . %{request_uri}/ [l,r=301] # internally forward /dir/foo /dir/foo.php rewritecond %{request_filename} !-d rewritecond %{request_filename}.php -f rewriterule ^(.*?)/?$ $1.php [l] we can rewrite urls using .htaccess files. before writing in .htaccess files need verify kind of server using. can check server adding a <?php phpinfo(); ?> in php page. ensure mod_rewrite module enabled in apache server. can identified checking phpinfo included page. common methods used url rewriting follows ...
Read more

inno setup - TLabel or TNewStaticText - change .Font.Style on Focus like Cursor changes with .Cursor -

is possible change .font.style on focus tlabel or tnewstatictext happens cursor when use .cursor ? there no built-in support track mouse hovering in inno setup @ time. however, intercepting window procedure of controls can track yourself. following example need innocallback library: [setup] appname=my program appversion=1.5 defaultdirname={pf}\my program outputdir=userdocs:inno setup examples output [files] source: "innocallback.dll"; destdir: "{tmp}"; flags: dontcopy [code] #ifdef unicode #define aw "w" #else #define aw "a" #endif const gwl_wndproc = -4; wm_mousemove = $0200; type wparam = uint_ptr; lparam = longint; lresult = longint; twindowproc = function(hwnd: hwnd; umsg: uint; wparam: wparam; lparam: lparam): lresult; function setcapture(hwnd: hwnd): hwnd; external 'setcapture@user32.dll stdcall'; function releasecapture: bool; external 'releasecapture@user32.dll stdcall'; func...
Read more