Let's see if I can get through this third column on how objects are born without blushing. So far we've seen two patterns: “Objects from States” and “Objects from Collections.” This time we'll look at two more sources of objects: “Objects from Variables” and “Objects from Methods.” All four patterns have one thing in common—they create objects that would be difficult or impossible to invent before you have a running program.

These patterns are part of the reason I am suspicious of any methodology that smacks of the sequence, “design, then program.” The objects that shape the way I think about my programs almost always come out of the program, not out of my preconceptions. Thinking “the design phase is over, now I just have to push on and finish the implementation” is a sure way to miss these valuable objects and end up with a poorly structured, inflexible application to boot.