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Metamodels

A metamodel is a model whose instances are models.¹ A GenVoca model of a product line is a tuple whose components are features (0-ary or 1-ary functions). An extension (a.k.a. delta or refinement) of a model is a "meta-feature", which is a tuple of deltas that can modify an existing product line by modifying existing features and adding new features. As a simple example, consider GenVoca model M that contains three features a-c:

M = [ a , b , c ] {\displaystyle M=[a,b,c]}

Suppose meta-model MM contains three meta-features AAA-CCC, each of which is a tuple with a single non-identity feature:

M M = [ A A A , B B B , C C C ] = [ [ a , 0 , 0 ] , [ 0 , b , 0 ] , [ 0 , 0 , c ] ] {\displaystyle {\begin{aligned}MM&=[AAA,BBB,CCC]\\&=[[a,0,0],[0,b,0],[0,0,c]]\end{aligned}}}

where 0 is the null feature. Model M is constructed by adding the meta-features of MM, where + is the composition operation (see FOSD).

M = A A A + B B B + C C C expression = [ a , 0 , 0 ] + [ 0 , b , 0 ] + [ 0 , 0 , c ] substitution = [ a + 0 + 0 , 0 + b + 0 , 0 + 0 + c ] composition = [ a , b , c ] simplification where  0 + x = x + 0 = x {\displaystyle {\begin{aligned}M&=AAA+BBB+CCC&{\text{expression}}\\&=[a,0,0]+[0,b,0]+[0,0,c]&{\text{substitution}}\\&=[a+0+0,0+b+0,0+0+c]&{\text{composition}}\\&=[a,b,c]&{\text{simplification where }}0+x=x+0=x\end{aligned}}}

MM models a product line of product lines (PL**2). That is, different MM expressions correspond to GenVoca models of different product lines..

See also

• Feature-oriented programming – basic overview
• FOSD origami
• FOSD program cubes – multi-dimensional product lines
• FOSD feature interactions – other operations on features, including an operation designating feature interaction

References

1. "Scaling Step-Wise Refinement" (PDF). ftp://ftp.cs.utexas.edu/pub/predator/TSE-AHEAD.pdf ↩