Hands-On Design Patterns and Best Practices with Julia

Code generation for function definitions

Code generation is one way to tackle this problem, as mentioned in the preceding section. What we will do is to build up the syntax of defining the function and then throw that into a loop to define all three logging functions. Here is how the code may look:

for level in (:info, :warning, :error)    lower_level_str = String(level)    upper_level_str = uppercase(lower_level_str)    upper_level_sym = Symbol(upper_level_str)    fn = Symbol(lower_level_str * "!")    label = " [" * upper_level_str * "] "    @eval function $fn(logger::Logger, args...)        if logger.level <= $upper_level_sym            let io = logger.handle                print(io, trunc(now(), Dates.Second), $label)                for (idx, arg) in enumerate(args)                    idx > 0 && print(io, " ") print(io, ...