How about using 4., but instead of copying redundant data/fields into each variant, put this common material into a small file and "include" it in each of the variants? Then only a single version needs to be edited and maintained.
--Peter P.S. BlackBoxOptim is a great contribution. I plan to make heavy use of it in the near future in designing hardware. On Tuesday, February 25, 2014 10:44:46 PM UTC-8, Robert Feldt wrote: > > I really like Julia's dispatch mechanisms, type system and so on. I have > found a number of different ways I use it to design libraries and programs. > But it would be great with some patterns/ideas/feedback from more seasoned > Julia programmers. What are your Julia Design Patterns? > > A concrete situation that I have struggled somewhat with is how to best > design in Julia for the situation where I have one main/default > algorithms/set-of-behaviors+data but then with a multitude of small > variations. Typically there is a large set of data and methods/functions > that are the same for the whole class of things and there are only 1-4 > functions/methods that need to change for each variation. An example from > BlackBoxOptim ( https://github.com/robertfeldt/BlackBoxOptim.jl ) is > where there is one type for DifferentialEvolution and then multiple > different variants of DE where only 1-2 functions differ from the "base" DE > one. > > I have found a few different "design patterns" for this situation but not > sure what is the long-term best: > > 1. Have a few Function fields in the "base" (composite) type which are set > up at construction time and that implements the variant-specific behaviors. > This is simple and direct but feels a bit "un-Julia" since it does not > really use the dispatch system. One also has to predict the variation > points (here: function) upfront which might not be flexible enough. Also > performance might suffer since the types of the function not known. > > 2. Have one XBase type which includes a field of an abstract XStrategy > type where specific sub-types to XStrategy implements each variant by > implementing variant-specific functionality. This seems fairly efficient, > but again one has to predict more or less where the variations should > happen since the functions on the XBase type need to call to the XStrategy > functions. > > 3. Have one XBase type which is then included as a field in specific > variants. This seems efficient and flexible but the code is somewhat > cluttered in that one has to have one extra indirection when accessing > common data/fields (this is a similar problem in 2 above though). > > 4. "Copy" the common data/fields of XBase into each specific variant. This > is the most flexible and should have high performance but there seem to be > a risk that bugs have to be changed in multile source code locations since > it is a kind of "copy-paste reuse". > > Would be great to hear your advice/feedback on how you design in/with the > Julia type and dispatch system. > > Thanks, > > Robert Feldt >
