Odd error with g++

I am getting this linking error. Any idea of what is means and where I
can look for a solution?


/bin/sh ../libtool --tag=CXX --mode=link g++ -O0 -g3 -Wno-deprecated -o
job_file job_file.o jobfile.o jobfilereader.o
mkdir .libs
g++ -O0 -g3 -Wno-deprecated -o job_file job_file.o jobfile.o
jobfilereader.o
jobfile.o: In function `JobFile':
/home/wchapman/project/shared_logic/job_file/src/jobfile.cpp:4:
undefined reference to `vtable for JobFile'
/home/wchapman/project/shared_logic/job_file/src/jobfile.cpp:4:
undefined reference to `vtable for JobFile'
/home/wchapman/project/shared_logic/job_file/src/jobfile.cpp:9:
undefined reference to `vtable for JobFile'
/home/wchapman/project/shared_logic/job_file/src/jobfile.cpp:9:
undefined reference to `vtable for JobFile'
jobfile.o: In function `~JobFile':
/home/wchapman/project/shared_logic/job_file/src/jobfile.cpp:15:
undefined reference to `vtable for JobFile'
jobfile.o:/home/wchapman/project/shared_logic/job_file/src/jobfile.cpp:15:
more undefined references to `vtable for JobFile' follow
jobfilereader.o:(.gnu.linkonce.r._ZTI13JobFileReader+0x8): undefined
reference to `typeinfo for JobFile'
collect2: ld returned 1 exit status

What is a vtable? What does this mean?

Basically, I have a object JobFile and a object JobFileReader that
inherits it. I am trying to instaniate a JobFileReader class for
testing. Im using kdevelop if it helps.

Thanks,
Will

.