Small grammar addition for c++0x. Why not?
in [C++]
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From: Martin York on 28 Mar 2008 20:03 On Mar 28, 9:43 am, german diago <germandi...(a)gmail.com> wrote: > Hello. I'd like to propose a small grammar addition for inclusion in c+ > +0x. It's quite simple, and I wonder why this isn't allowed in the > current language. Example. > > using namespace std; > using namespace boost; > using namespace mylib; > using namespace anotherlibr; > > using lib2::variable1; > using lib2::variable2; > using lib2::variable3; > using lib3::variable4; > > Why not? > > using namespace std, boost, mylib, anotherlibr; > using lib2::variable, lib2::variable2, lib2::variable3, > lib3::variable4; > > It's more compact. Just that. I see no reason not to extend the > grammar to allow this. Its' already supported. try: #include <iostream> using std::cout; // Global. int main() { using std::cin; // Local to this scope only cout << "Hit any key to continue\n"; char val; cin >> val; } void plop() { int x; std::cin >> x; // need to use std:: here because // the previous using has only local scope. } -- [ See http://www.gotw.ca/resources/clcm.htm for info about ] [ comp.lang.c++.moderated. First time posters: Do this! ]
From: Francis Glassborow on 29 Mar 2008 04:47 german diago wrote: > Hello. I'd like to propose a small grammar addition for inclusion in c+ > +0x. It's quite simple, and I wonder why this isn't allowed in the > current language. Example. > > using namespace std; > using namespace boost; > using namespace mylib; > using namespace anotherlibr; > > using lib2::variable1; > using lib2::variable2; > using lib2::variable3; > using lib3::variable4; > > Why not? > > using namespace std, boost, mylib, anotherlibr; > using lib2::variable, lib2::variable2, lib2::variable3, > lib3::variable4; > > It's more compact. Just that. I see no reason not to extend the > grammar to allow this. We have considered that more than once and decided that we did not want to provide it. Good programming practice is to allow only one declaration per statement. Legacy prevents us from doing that with declarations of variables etc. but we saw no reason to extend yhat to multiple namespace declarations/directives. -- [ See http://www.gotw.ca/resources/clcm.htm for info about ] [ comp.lang.c++.moderated. First time posters: Do this! ]
From: d04rp on 29 Mar 2008 06:43 > Hello. I'd like to propose a small grammar addition for inclusion in c+ > +0x. It's quite simple, and I wonder why this isn't allowed in the > current language. Example. > > using namespace std; > using namespace boost; > using namespace mylib; > using namespace anotherlibr; > > using lib2::variable1; > using lib2::variable2; > using lib2::variable3; > using lib3::variable4; > > Why not? Ofcourse this _could_ be added. But is it really necessary? It's nothing more than syntactic sugar. Also its like declaring variables like this: int value1, value2, value3; Widget w1, w2, w3; And I'm not recommending you to declare your variables like that. It's more "maintenance friendly" to declare them like this: int value1; int value2; int value3; Widget w1; Widget w2; Widget w3; HTH. Roger Schildmeijer -- [ See http://www.gotw.ca/resources/clcm.htm for info about ] [ comp.lang.c++.moderated. First time posters: Do this! ]
From: Ni on 31 Mar 2008 01:43 > And shorter code is always > more readable. It is not a true. as for me if ( a = getA() > b = getB() && i++ > count ) it is not a good line of code, but short. The advantage of per line records is you can comment out one fast and independently. -- [ See http://www.gotw.ca/resources/clcm.htm for info about ] [ comp.lang.c++.moderated. First time posters: Do this! ]
From: Gerhard Menzl on 31 Mar 2008 01:43
german diago wrote: > On 29 mar, 22:43, d0...(a)student.lth.se wrote: >> And I'm not recommending you to declare your variables like that. It's >> more "maintenance friendly" to declare them like this: >> int value1; >> int value2; >> int value3; >> >> Widget w1; >> Widget w2; >> Widget w3; > > > I don't think that's much more mantainable than the shorter > declarations. You could get confused with > int * a, b; > Which means a is int * but b is just int. I don't think that's an > argument for what you explained. Restricting code to one declaration per line is both more readable and maintainable. It is more readable because it doesn't force you to filter out all the intervening identifiers when you want to look up the type of a single variable. There is a reason why in ordinary text important items are listed on separate lines, often supported by bullets or numbers. If fewer lines meant more readability, newspapers would have landscape format and no columns. It is more maintainable because it is much easier to add, move, or delete lines than parts of lines. -- Gerhard Menzl Non-spammers may respond to my email address, which is composed of my full name, separated by a dot, followed by at, followed by "fwz", followed by a dot, followed by "aero". [ See http://www.gotw.ca/resources/clcm.htm for info about ] [ comp.lang.c++.moderated. First time posters: Do this! ] |