General talk about software patterns

[Shijing Lu <shijing.lu AT gmail.com>]

Dear all:

• I have a class named "A". Originally it has five members, but later I add or delete some members of it. Then I have to rewrite its save and load function. Then it can not load former saved files.
  
• Some times I combine data and functions in a single class which has multitudinous functions. Some functions therein have similar but slightly different codes, for example. _calculateKinecitcEnergy() and _calculateTotalEnergy(). Both functions have a time consuming loop, so it is impossible to call the former one from the later on, therefore I have to write some pieces of codes at least twice in one class. Every time when I modify the class, it is exaustive to search around class for similar codes. 
• Is there any effective and concise design for this?

Thank you in advance.