From -5140387494031054424 X-Google-Language: ENGLISH,ASCII-7-bit X-Google-Thread: 109fba,e5334c2e3a820d75,start X-Google-Attributes: gid109fba,public X-Google-Thread: f78e5,e5334c2e3a820d75,start X-Google-Attributes: gidf78e5,public From: "Ivo" Subject: Q: Const Reference as Default Parameter Date: 2000/05/24 Message-ID: <8gbfo7$3r9$1@as102.tel.hr>#1/1 X-Deja-AN: 626352704 Content-Transfer-Encoding: 7bit Approved: Fergus Henderson , moderator of comp.std.c++ X-Priority: 3 X-Authentication-Warning: mulga.cs.mu.OZ.AU: fjh set sender to devnull@stump.algebra.com using -f Content-Type: text/plain; charset=US-ASCII X-MimeOLE: Produced By Microsoft MimeOLE V5.00.2919.6700 X-Complaints-To: abuse@demon.net X-Mail2News-Path: news.demon.net!mulga.cs.mu.oz.au X-Trace: mail2news.demon.co.uk 959100365 mail2news:20393 mail2news mail2news.demon.co.uk Organization: HiNet X-MSMail-Priority: Normal X-Robomod: STUMP, ichudov@algebra.com (Igor Chudov) Mime-Version: 1.0 NNTP-Posting-Date: 22 May 2000 14:20:55 GMT Newsgroups: comp.lang.c++,comp.std.c++ Suppose I have a class C and a function void f(const C&); Now, I want to provide a default argument for this function, something like void f(const C& c=C()); (provided that class C defines a meaningful public default constructor). Unfortunately, this construct is not aligned with the latest C++ standard. Indeed, MSVC++ (debug mode only) would report a warning, while GNU C++ compilers would report an error. To apply a fixture, I can declare something like void f(const C& c=(C&)(const C&)C()); Otherwise, I can overload my function f void f(const C&); void f() {C c; f(c);}; In the case I need it frequently, for different classes and their various constructors (with or without parameters), I can (reluctantly) use a macro definition: TEMP_OBJ_INST(T) (T&)(const T&)T void f(const C& c=TEMP_OBJ_INST(C)()); void g(const D& d=TEMP_OBJ_INST(D)(-1, 3.14)); - where D was another class with public constructor D(int, double). Is there any other, more elegant way to put it right? Thanks, Ivo --- [ comp.std.c++ is moderated. To submit articles, try just posting with ] [ your news-reader. If that fails, use mailto:std-c++@ncar.ucar.edu ] [ --- Please see the FAQ before posting. --- ] [ FAQ: http://reality.sgi.com/austern_mti/std-c++/faq.html ]