I have often done it that way, too. In this case I decided to use a #lang for a few reasons:
- The values for some of the parameters are not readable. - In some cases I want to do a little bit of work to calculate the value. For instance, "production.rkt" reads in the values of some API keys from a file not tracked in the git repository. - I have more than just two different configurations, e.g. for local automated testing vs. interactive local use. - I have some colleagues working on other aspects of the project who have little to no Racket experience, but who may need to edit the configuration files. Especially with syntax-parse, making a small #lang gets some free IDE support and good, early error messages if e.g. they enter a string where there should have been a number. (Plus, it does show off how wonderful Racket is.) The #lang essentially just redefines #%module-begin so that the module defines and exports a function "config" (actually a struct with prop:procedure) that calls a thunk with the intended parameterization. Ultimately I actually found that writing a #lang was fairly comparable to the amount of code I would have needed to get good error reporting with the read-based option, so I'm pretty happy with it. Philip On Mon, May 1, 2017 at 2:59 AM, Alex Harsanyi <alexharsa...@gmail.com> wrote: > Hi Philip, > > I don't have an answer to your problem, but I'm curious as to what do you > store in "local.rkt" and "production.rkt" to justify such a complicated > solution. > > In the projects that I worked on (Racket or otherwise), local vs > production differ in the values for different parameters, which are just > key => value mappings. In Racket, I would just store these as association > lists in "local.rktd" and "production.rktd" than in the code just to a: > > (define config-file (if (prodution?) "production.rktd" "local.rktd")) > (define config (call-with-input-file config-file read)) > > Than just use `assoc` to find the values for the parameters. > > Best Regards, > Alex. > > On Monday, May 1, 2017 at 9:03:45 AM UTC+8, Philip McGrath wrote: > > I'm working on a #lang for configuration files for a larger project I'm > working on, and I'm trying to find a setup that meets my (largely cosmetic) > goals without producing a "standard-module-name-resolver: cycle in > loading" error. > > > > > > Given the following directory structure: > > my-project/config.rktconfig/local.rktproduction.rkt > > I would like both to write "local.rkt" and "production.rkt" in "#lang > my-project/config" and to have "(require my-project/config)" provide > bindings re-exported from "local.rkt" and "production.rkt" and some extra > bindings for working with those values. > > > > > > This seems like it should be doable, because there aren't any logical > cyclic dependencies, but I haven't found a way to convince Racket of that. > > > > > > I initially tried making a "my-project/config/lang/" directory with a > "module-lang.rkt" and a "reader.rkt" consisting of "(module reader > syntax/module-reader my-project/config/lang/module-language)", then > having "config.rkt" require and re-export "local.rkt", "production.rkt", > and the appropriate exports of "module-lang.rkt", but this gave me a "cycle > in loading" error. > > > > > > My first guess was that the problem might be that Racket was looking for > a reader submodule of "config.rkt", so I re-wrote "module-lang.rkt" and > "reader.rkt" as submodules of "config.rkt" (with "module", not "module*" or > "module+"), but this didn't solve the problem. > > > > > > Is there a way to do what I want? > > > > > > -Philip > > -- > You received this message because you are subscribed to the Google Groups > "Racket Users" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to racket-users+unsubscr...@googlegroups.com. > For more options, visit https://groups.google.com/d/optout. > -- You received this message because you are subscribed to the Google Groups "Racket Users" group. To unsubscribe from this group and stop receiving emails from it, send an email to racket-users+unsubscr...@googlegroups.com. For more options, visit https://groups.google.com/d/optout.
