Class DistanceFromMainSequence

Distance from Main Sequence metric (D)

Robert Martin's metric that measures how far a component is from the ideal balance between abstractness and instability.

Formula: D = |A + I - 1| Where:

• A = Abstractness (0 to 1)
• I = Instability (0 to 1)
• The main sequence is the line A + I = 1

Interpretation:

• D = 0: On the main sequence (ideal)
• D closer to 0: Better design
• D closer to 1: Further from ideal balance

When applied to files (file-wise analysis):

• Files that are abstract and stable (A high, I low) are on the main sequence
• Files that are concrete and unstable (A low, I high) are on the main sequence
• Files that are abstract and unstable are in the Zone of Uselessness
• Files that are concrete and stable are in the Zone of Pain