> Linking CXX shared library lib/libmidas.so
/usr/bin/c++  ... -o lib/libmidas.so ... CMakeFiles/midas-shared.dir/src/history_odbc.cxx.o 
CMakeFiles/midas-shared.dir/src/history_sql.cxx.o 
CMakeFiles/midas-shared.dir/src/history_sql.cxx.o: In function `SqlODBC':
/opt/DAQ/repos/bot/midas/src/history_sql.cxx:200: multiple definition of `SqlODBC::SqlODBC()'
CMakeFiles/midas-
shared.dir/src/history_odbc.cxx.o:/opt/DAQ/repos/bot/midas/src/history_odbc.cxx:315: first defined 
here
> Why is the class "SqlODBC" duplicated?

This is interesting. I do not think my C++ book spells it out that I cannot have class A in foo.cxx
and a class A in bar.cxx. In fact I already discovered that the two classes A will collide (duplicate default 
constructor A::A, even if all other member functions are different) if I link an executable that uses both 
foo.o and bar.o.

Is there a way around this problem? In C, I can declare functions and variables "static" to "hide" them
from the linker.

What is the C++ equivalent for classes? (Any C++ experts here?)

In this specific case, the file history_odbc.cxx will disappear with the next commit of mhttpd, hopefully 
today. mlogger and mh2sql already do not use it.

And I will commit the Makefile change renaming libmidas.so to libmidas-shared.so, so we can build it 
by default but still link midas core executables to the normal midas library.

This will catch such a problem if it happens again.

K.O.