public inbox for gcc-prs@sourceware.org help / color / mirror / Atom feed
From: Jason Stanek <jstanek@iastate.edu> To: nobody@gcc.gnu.org Cc: gcc-prs@gcc.gnu.org, Subject: Re: c++/8567: std::endl is of unknown type when overloading operator<< (repeat in case attachment didnt work) Date: Thu, 21 Nov 2002 06:26:00 -0000 [thread overview] Message-ID: <20021115031602.17636.qmail@sources.redhat.com> (raw) The following reply was made to PR c++/8567; it has been noted by GNATS. From: Jason Stanek <jstanek@iastate.edu> To: bangerth@dealii.org, gcc-bugs@gcc.gnu.org, gcc-prs@gcc.gnu.org, jstanek@iastate.edu, jstanek@vrac.iastate.edu, nobody@gcc.gnu.org, gcc-gnats@gcc.gnu.org Cc: Subject: Re: c++/8567: std::endl is of unknown type when overloading operator<< (repeat in case attachment didnt work) Date: Thu, 14 Nov 2002 21:13:20 -0600 Isnt there a way to specify a default template type? So instead of declaring endl as a pure template, it has a default type in the case that you dont specify one. Something like this: namespace std { template <typename T=int> T& endl (T&); }; -Jason At 11:37 PM 11/14/2002 +0000, you wrote: >Synopsis: std::endl is of unknown type when overloading operator<< (repeat >in case attachment didnt work) > >State-Changed-From-To: open->closed >State-Changed-By: bangerth >State-Changed-When: Thu Nov 14 15:37:17 2002 >State-Changed-Why: > Not a bug. Basically, it is this: > --------------------------------- > namespace std { > template <typename T> T& endl (T&); > }; > > class BlackHole{}; > > template <typename T> BlackHole& operator<<(BlackHole& bh, const T& > dummy); > template <typename T> BlackHole& operator<<(BlackHole& bh, T& > (*dummy)(T&)); > > int main() { > BlackHole bh; > bh << std::endl; > } > ------------------------------- > Since there is no unambiguous function std::endl, the > compiler cannot know which one to take as argument, so > you have to disambiguate the situation by passing it the > exact template argument list. Alternatively, you can give > an overloaded non-template op<<; in this example, this > would do: > BlackHole& operator<<(BlackHole& bh, int& (*dummy)(int&)); > Then std::endl<int> would be taken. > > W. > >http://gcc.gnu.org/cgi-bin/gnatsweb.pl?cmd=view%20audit-trail&database=gcc&pr=8567
next reply other threads:[~2002-11-15 3:16 UTC|newest] Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top 2002-11-21 6:26 Jason Stanek [this message] -- strict thread matches above, loose matches on Subject: below -- 2003-05-10 17:46 Dave Brondsema 2002-11-21 7:18 Wolfgang Bangerth 2002-11-21 4:17 bangerth 2002-11-20 4:46 jstanek
Reply instructions: You may reply publicly to this message via plain-text email using any one of the following methods: * Save the following mbox file, import it into your mail client, and reply-to-all from there: mbox Avoid top-posting and favor interleaved quoting: https://en.wikipedia.org/wiki/Posting_style#Interleaved_style * Reply using the --to, --cc, and --in-reply-to switches of git-send-email(1): git send-email \ --in-reply-to=20021115031602.17636.qmail@sources.redhat.com \ --to=jstanek@iastate.edu \ --cc=gcc-prs@gcc.gnu.org \ --cc=nobody@gcc.gnu.org \ /path/to/YOUR_REPLY https://kernel.org/pub/software/scm/git/docs/git-send-email.html * If your mail client supports setting the In-Reply-To header via mailto: links, try the mailto: linkBe sure your reply has a Subject: header at the top and a blank line before the message body.
This is a public inbox, see mirroring instructions for how to clone and mirror all data and code used for this inbox; as well as URLs for read-only IMAP folder(s) and NNTP newsgroup(s).