Issue with using dlib/threads

[Gregory Sharp]

Hi, I thought to try out dlib's thread wrapper. I created a program like below:

#include "dlib/threads.h"
int main () {
return 0; 
}

This gives me the below error. Any idea what is happening? This is dlib 18.7 with MSVC 9.

Thanks!
Greg

1>dlib_thread_test.obj : error LNK2019: unresolved external symbol _USER_ERRORviolation_of_one_definition_rule_detectedinconsistent_use_of_DEBUG_or_ENABLE_ASSERTS_preprocessor_directives referenced in function _dlib_check_consistent_assert_usage
1>C:\gcs6\build\vs2008\plastimatch-3.20.1-dcmtk\Release\dlib_thread_test.exe : fatal error LNK1120: 1 unresolved externals

[Davis]

You probably forgot to add dlib/all/source.cpp into your application.

Cheers,
Davis

[Gregory Sharp]

Just figured that out! I'm so used to using dlib as header only. Thanks Davis!

[Davis]

No problem :)

Cheers,
Davis

[Gregory Sharp]

Just figured that out! I'm so used to using dlib as header only. Thanks Davis!

[Gregory Sharp]

I still have a problem with this. It seems that I will need to replicate the code within each DLL that uses it. Or else, if I want to centralize the dlib functions within a single DLL, I should write my own wrapper functions (with my own header files that don't include dlib header files) which call the dlib functions. Otherwise, I get the same link error.

Also, the dlib don't look like they respect declspec decorations, no?

[Davis]

I would recommend statically compiling dlib into your dlls.

Right, I haven't put any declspec annotations anywhere in dlib and in
general making shared libraries from C++ code is quite problematic.
Especially with visual studio and it's various different runtimes. See
also http://dlib.net/howto_contribute.html#9.

So I would really just statically compile it in. If you really care
about binary size you can include the individual cpp files from dlib
(rather than dlib/all/source.cpp which includes everything) and that
will cut down on the size.

Cheers,
Davis

[Gregory Sharp]

OK, I understand. Thanks!

[Davis]

No problem :)

[Samuel]

Hi, i’m having a similar issue with svm_threaded but adding dlib/all/source.cpp to my project source files results in lots of linker errors (this happen with mingw). But on visual studio it doesn't change anything, though I won't say I totally understand what you mean by adding the source.cpp to my application, please I'll need your help in this regard.

[Davis]

How exactly are you compiling it and what are the errors?

Cheers,
Davis

[kHenry]

I have a similar problem. I'm using dlib with my dll library. Specifically, the dlib is static library and the dlib is linked with my dll library. I just want to link my dll library when I want to use dlib. So, I made new project and I linked my dll library which has static dlib. But it made an error like this:

unresolved external symbol USER_ERRORmissing_dlib_all_source_cpp_fileOR__inconsistent_use_of_DEBUG_or_ENABLE_ASSERTS_preprocessor_directives_

can I fix this error?

[Davis]

It means you aren't consistently #defining DEBUG or ENABLE_ASSERTS in your
code. Some .cpp files are compiled with one or both of those preprocessor
macros defined while others are not, resulting in a violation of C++'s one
definition rule (see http://en.wikipedia.org/wiki/One_Definition_Rule).
Moreover, you should probably read this article that talks about the
difficulties of using C++ inside dlls:
http://siomsystems.com/mixing-visual-studio-versions/. The short summary
is don't use dlls.

[Chaithra Kumari]

Hi,

I am working on dlib from past 2 weeks.I want to step into cpp file of function (Means I want to see the source code) as i was doing in opencv.Can you please help me to find?