Molstructure object

Here is a real-world example for illustrative purposes. Suppose you have a chemical information system that has to support both Molfile and Smiles structures and a business method in a business object has to get the mol-weight and molformula from the Molstructure objects to fulfill its responsibilities. A naive design is to have two versions of the business method one takes a Molfile structure object as input and another takes a Smiles structure as input (Figure 2.4). 

The other instance variables in the Compound class include a Molstructure object, a list of salt structures, a list of parent structures, a String array that contains information about what has been changed or what the problems are in the structure as a result of the chemistry rules checking, and a Compounds tate object representing the current state of the Compound object. The process() method in the Compound object simply delegates the call to its current state object, which knows how to process the Compound object depending on its current state as described above. 

Molstructure is similar to the Quantity object described in Martin Fowler s Analysis Patterns book (Fowler, 1996) in that it has a format (unit) and a value. 

---