On Wed, May 14, 2014 at 12:35 PM, J. Ian Johnson <i...@ccs.neu.edu> wrote: > tl;dr if you use struct-info in your programs, I might break them. Please > continue reading. > > I had a PR a while ago suggesting a change to struct-copy due to its > unhygienic nature with fields. It did not go through since there wasn't > enough information in the struct-info to separate the struct-name and the > field-name. Because struct-info does not have a procedural-only interface, > changing it to instead or also hold the individual field identifiers would be > backwards incompatible. However, I also expect that struct-info manipulation > outside of core Racket is rare. > > Is there anyone out there that would be affected by a this change that would > be unwilling to make slight modifications to support the new struct-info? > I ask not because of struct-copy itself, but for an additional enhancement to > racket/match: named field selection from structs instead of positional only. > I'm getting bitten by pervasive refactoring woes whenever I add fields to > structs. All of my match patterns must change to have an extra _ somewhere.
I don't understand why this would require a backwards-incompatible change to struct-info. Also, this discussion is confusing because it's not clear whether you mean the dynamic value produced by the `struct-info` procedure, or the structure type transformer binding. I think you mean the latter, in which case I expect you could do what you want by implementing `prop:struct-info` appropriately with an extended structure, and handling existing values (such as six-element lists) appropriately with defaults. Sam ____________________ Racket Users list: http://lists.racket-lang.org/users
