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Confused about friend operators, namespaces, and private members...
From: |
Robert Heller |
Subject: |
Confused about friend operators, namespaces, and private members... |
Date: |
Tue, 17 Nov 2009 15:56:08 -0600 |
I am using gcc 3.4.6 under CentOS 4.8 (RHEL 4.8):
Reading specs from /usr/lib/gcc/i386-redhat-linux/3.4.6/specs
Configured with: ../configure --prefix=/usr --mandir=/usr/share/man
--infodir=/usr/share/info --enable-shared --enable-threads=posix
--disable-checking --with-system-zlib --enable-__cxa_atexit
--disable-libunwind-exceptions --enable-java-awt=gtk
--host=i386-redhat-linux
Thread model: posix
gcc version 3.4.6 20060404 (Red Hat 3.4.6-11)
And I am getting errors like this:
./../../C++/ParserClassesBoost/TrackGraph.cc: In function
`Parsers::TrackGraph::Transform2D* operator*(const
Parsers::TrackGraph::Transform2D&, const Parsers::TrackGraph::Transform2D&)':
./../../C++/ParserClassesBoost/TrackGraph.h:747: error: `float
Parsers::TrackGraph::Transform2D::matrix[3][3]' is private
./../../C++/ParserClassesBoost/TrackGraph.cc:675: error: within this context
./../../C++/ParserClassesBoost/TrackGraph.h:747: error: `float
Parsers::TrackGraph::Transform2D::matrix[3][3]' is private
./../../C++/ParserClassesBoost/TrackGraph.cc:675: error: within this context
./../../C++/ParserClassesBoost/TrackGraph.h:747: error: `float
Parsers::TrackGraph::Transform2D::matrix[3][3]' is private
./../../C++/ParserClassesBoost/TrackGraph.cc:676: error: within this context
make[1]: *** [libMRRParserClassesBoost_la-TrackGraph.lo] Error 1
make[1]: Leaving directory
`/home/heller/Deepwoods/ModelRRSystem/Linux/C++/ParserClassesBoost'
make: *** [all] Error 2
Here is the relevant fragment of TrackGraph.cc:
using namespace Parsers;
TrackGraph::Transform2D* operator * (const TrackGraph::Transform2D& t1, const
TrackGraph::Transform2D& t2)
{
TrackGraph::Transform2D *new_t = new TrackGraph::Transform2D;
for(int i=0; i < 3; i++)
for(int j=0; j < 3; j++) {
float sum = 0.0;
for(int k=0; k < 3; k++)
sum += t1.matrix[j][k] * t2.matrix[k][i];
new_t->matrix[j][i] = sum;
}
return new_t;
}
And of TrackGraph.h:
namespace Parsers {
class TrackGraph {
public:
class Transform2D {
private:
/** Transform matrix.
*/
float matrix[3][3];
/** Fuzz factor.
*/
const static float FUZZ = .00001;
public:
/** Matrix multiplication.
*/
friend Transform2D* operator * (const Transform2D& t1,const
Transform2D& t2);
};
};
};
I don't understand these error messages. They didn't happen before I
added the namespace code. I would *like* to embed my code in a
namespace and not put random stuff into the global namespace, but
either gcc 3.4.6 does not handle namespaces well when dealing with
friend operators or I am doing something wrong, but I don't know what
that could be. For various reasons I don't want to install a newer
version of gcc (I want to stay binary compatible with the rest of my
system).
--
Robert Heller -- 978-544-6933
Deepwoods Software -- Download the Model Railroad System
http://www.deepsoft.com/ -- Binaries for Linux and MS-Windows
heller@deepsoft.com -- http://www.deepsoft.com/ModelRailroadSystem/
- Confused about friend operators, namespaces, and private members...,
Robert Heller <=
- Re: Confused about friend operators, namespaces, and private members..., Thomas Maeder, 2009/11/18
- Re: Confused about friend operators, namespaces, and private members..., address@hidden, 2009/11/18
- Solved: Confused about friend operators, namespaces, and private members..., Robert Heller, 2009/11/18