Implement a new data type

[mohand oubelkacem makhoukhene <mohand-oubelkacem@xxxxxxxxxxx>]

Hello

I would like to implement a new data type next to char, number, varchar... for example a special "Money" type, but

I don't want to use extensions and the Create type command.  I want to implement it directly inside source code,

because I want to implement my new type at lower level, in order to perform some more sophisticated functions after.

Just as an example,  help the optimizer in its decisions.

How should I proceed ? Is it an easy task ?

Thanks

Mohand