Create a new table based on an already existed table (through Lua or C API)?

[孙世龙 sunshilong <sunshilong369@...>]

How to create a new table based on an already existed table (through
Lua or C API)?

This code snippet seems impossible to achieve this goal:

foo = {};
foo.a = 1;
foo.b = 2;

new = foo;
print(new, foo)  --they both point to the same table!

new.a = new.a+1;  --the value of foo.a has been modified too.
                              --I hope the table named `new` to be a
table which is independent from the table named `foo`.