Julia: Structuring code with many different but related algorithm choices

Question

I am looking for an elegant way to re-arrange my code. For developing solvers, what happens is you can have a lot of different options which have the same setup. For example

Answer 1

I am not sure if this is a better approach than using a state object, but you can use macros to achieve what you want:

macro f() 
    quote 
        b = 5
        x = a * b
        x  # the value of a block is equal to its last statement
    end
end

function foo()
    a = 2
    b = 3
    x = @f()
    x, b  # (10,3)
end

Note that Julia automatically replaces b and x within the macro with a unique name to avoid side effects. If you want to have side effects, you can use the following:

macro g() 
    esc(quote 
        b = 5
        x = a * b
    end)
end

function bar()
    a = 2
    b = 3
    @g()
    x, b  # (10,5)
end

This is equivalent to replacing @g() with the code between quote and end from the definition of g. One can also define a small convenience macro:

macro def(name, definition)
    return quote 
        macro $(esc(name))()
            esc($(Expr(:quote, definition)))
        end
    end
end

With that, g could have been defined as

@def g begin
    b = 5
    x = a*b
end