For the record, a workable solution, at least for this particular code: I pass all output through wrapout() at the outermost output call. The object to be printed is traversed recursively. All types fall through except for the handful that I want to change. Each of these is each wrapped in a new type. I extend Base.show for each of these wrapper types. This seems pretty economical and robust and works across versions. The wrapper types are only introduced upon output, the rest of the code never sees them.
This works because the code uses a customization of the REPL, and several instances of print, warn, string, etc. I make a new top-level output function for the REPL that uses `wrapout`. I also generate wrappers for each of print, etc. that map `wrapout` over all arguments. A developer is expected to use the interface provided rather than `print` etc. directly. The user doesn't even have a choice. There are very few types in the package, but a lot of nested instances. So there is very little code needed to traverse these instances. This might be more difficult in a different situation if many methods for wrapout() were required. On Monday, October 10, 2016 at 12:20:50 AM UTC+2, lapeyre....@gmail.com wrote: > > I want to change show for Symbol, Rational, and Bool. Till now, I simply > overwrote the existing methods. This works great. I get what I want, even > in warn and error and string interpolation, etc. It works flawlessly on > v0.4, v0.5, and v0.6. But, this changes the behavior for everyone. So, I > want to get the same effect through different means that do not affect > other code. Any idea about how to do this ? > > One solution is to copy a large amount of base code that uses print, > write, show, etc. renaming these functions. Other than changing 15 or 20 > lines for Symbol, etc., the code is unchanged. This is works more or less, > but is obviously a fragile, bad solution. > > Another idea is to make a subtype of IO that wraps subtypes of IO. I am > allowed to write methods for show for this new type. This is turning out to > be complicated and unworkable. > > Another vague idea is to make a new mime type. Another is to copy IOStream > as another type, so that I only have to write methods for Symbol, Rational > and Bool again. > > >
