Hi Darren, Thank you so much for taking time to write the illustrative example. That makes perfect sense.
I had the feeling that being explicit might be a better choice when projects get bigger. So far my codes are mainly for numerical studies in my research and are generally short, but I do want to keep a good style of coding as I expect myself to code more in future. Thanks, Darren. Zhongyi On Wed, Aug 31, 2011 at 7:09 PM, Darren Cook <dar...@dcook.org> wrote: > > Can I ask for specific reasons why people prefer explicit? Any potential > > danger for not being explicit? > > Hello Zhongyi, > It is hard to show in a toy example; in fact "using namespace" is best > for code examples where you want to get an idea across and not cloud it > with too much other code. > > But see the below example, and imagine the "//..." bits are dozens of > lines. When you see f(x) you don't know which function will be called. > You have to stop and search up to find the currently active namespace > definition. > The bigger your project, and the more 3rd party libraries you deal with, > the more this slows you down. > > See also: > http://www.parashift.com/c++-faq-lite/coding-standards.html#faq-27.5 > > Darren > > > //------------------------------------------ > > #include <iostream> > > namespace xx{ > double f(double x){ > return x*x; > } > } > > > namespace yy{ > double f(double y){ > return y+y; > } > } > > > void one(double x){ > using namespace xx; > //.... > std::cout<<f(x)<<"\n"; > } > > > void two(double x){ > using namespace yy; > //.... > std::cout<<f(x)<<"\n"; > } > > > > int main (int,char**){ > const double PI=3.14; > one(PI); > two(PI); > std::cout<<xx::f(PI)<<"\n"; > std::cout<<yy::f(PI)<<"\n"; > return 0; > } > > > -- > Darren Cook, Software Researcher/Developer > > http://dcook.org/work/ (About me and my work) > http://dcook.org/blogs.html (My blogs and articles) > _______________________________________________ > Rcpp-devel mailing list > Rcpp-devel@lists.r-forge.r-project.org > https://lists.r-forge.r-project.org/cgi-bin/mailman/listinfo/rcpp-devel >
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