Remove void pointer from Register's key

[Benardi]

Description

It has become increasingly counter-productive to employ a void pointer to store a primitive type (e.g., an integer or float). We should devise a new and more convenient strategy to store a primitive type in our Register.

Files

• src/include/register.h

Tasks

• Update Register struct
• Update source code and tests of modules that use the Register struct
• Update documentation of modules that use the Register struct