automatic template instanciation (g++, -frepo)

[Uwe Mayer]

Hi,

I am writing a library, which contains classes with template
memberfunctions. If I do not instanciate the templates I want to use, I get
an "undefined reference" link-error.

The FAQ
(http://www.new-brunswick.net/worksho...html#faq-35.15)
explained I had to explicitly name the instanciations I wanted to use. That
works, but is awfully tedious.

The gcc manual
(http://gcc.gnu.org/onlinedocs/gcc-4....-Instantiation)
suggests the use of the -frepo flag.

1. Did I understand it correctly, that this is supposed to handle the
automatic template instanciation, at the cost of longer compile /link time?

2. This also doesn't work. "collect2" is called, and the .rpo files are
generated, but now I even get a link error on something that looks like its
comming from STL:

[...]
collect: recompiling test6.cpp
collect: relinking
collect: recompiling test6.cpp
collect: relinking
test6-test6.o: In function `main':
test6.cpp:48: undefined reference to `ml::LinePlot&
ml::Axes::plot3<gsl_vector>(gsl_vector*, gsl_vector*, gsl_vector*, char*)'

libmatplot.so: undefined reference to `std::_Rb_tree<double,
std::pair<double const, ml::Axes*>, std::_Select1st<std::pair<double const,
ml::Axes*, std::less<double>, std::allocator<std::pair<double const,
ml::Axes* >::_M_erase(std::_Rb_tree_node<std::pair<double const,
ml::Axes**)'

Any ideas?
Thanks in advance
Ciao
Uwe

[BobR]

Uwe Mayer <me*****@hadiko.dewrote in message...

Hi,
I am writing a library, which contains classes with template
memberfunctions. If I do not instanciate the templates I want to use, I

get

an "undefined reference" link-error.

The gcc manual

(http://gcc.gnu.org/onlinedocs/gcc-4....ation.html#Tem
plate-Instantiation)

suggests the use of the -frepo flag.

1. Did I understand it correctly, that this is supposed to handle the
automatic template instanciation, at the cost of longer compile /link

time?

Did you read the "Where's the Template?" section in the GCC docs?

--
Bob R
POVrookie

[James Kanze]

On Aug 2, 3:15 pm, Uwe Mayer <[e-mail]:

I am writing a library, which contains classes with template
memberfunctions. If I do not instanciate the templates I want
to use, I get an "undefined reference" link-error.

That's curious. I never do.

The FAQ
(http://www.new-brunswick.net/worksho...html#faq-35.15)
explained I had to explicitly name the instanciations I wanted to use. That
works, but is awfully tedious.

I'm not too sure I understand what the FAQ is getting at here.
It puts the implementation of the function templates in a source
file; normally, you put them in the header, unless the template
is exported (and all of your target compilers support export).

The gcc manual
(http://gcc.gnu.org/onlinedocs/gcc-4....stantiation.ht...)
suggests the use of the -frepo flag.

Is this still supported? I thought that such options where just
there to handle compatibility issues with older compilers, like
CFront. At any rate, I never use them, and I've never had the
slightest problem.

For compilers which do use a repository, like Sun CC, you'll
probably need a special tool to build the library: for Sun CC,
for example, "CC -xar", rather than simply "ar". That tool will
normally be furnished with the compiler, however. And such is
not the case with g++; no special tool is needed, since g++
doesn't normally use a repository.

--
James Kanze (GABI Software) email:ja*********@gmail.com
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