[racket-dev] single-instantiation trick: kludgy workaround for planet packages?

From: Ryan Culpepper (ryanc at ccs.neu.edu)
Date: Tue Oct 5 22:37:17 EDT 2010

John Clements wrote:
> On Oct 5, 2010, at 3:25 PM, Ryan Culpepper wrote:
>> I seem to have mangled my response right before sending it. Here it is again, hopefully straightened out.
>> On 10/05/2010 03:59 PM, John Clements wrote:
>>> A couple of weeks ago, you showed me the trick that rackunit uses to allow single-instantiation of a modules.  I'm now trying to do this
>>> for a planet package, and it looks like I have to change the required module from being a relative to being an absolute path.  That is:
>>> (require (prefix-in drlink: private/drracket-link))
>> I assume (hope) you meant
>>  (require (prefix-in drlink: "private/drracket-link.rkt"))
>> for the relative require.
> yes, of course. My mistake.
>>> must become
>>> (require (prefix-in drlink: (planet "drracket-link.rkt" ("clements" "rsound.plt") "private")))
>>> This works, but seems extremely fragile.  Does it make sense to you that this would be required?  Without it, I get the error below:
>> From what I recall, the call to namespace-module-attach must use the correct absolute module path, but the require can be relative. I confirmed that that's how the last PLaneT version of schemeunit that included the tool (version (2 12)) did it.
>> It looks like you're using a PLaneT development link. Perhaps that's the source of the problem?
>> How about dropping the following code into drracket-link.rkt so it prints out its (absolute) resolved module path when it gets required from the tool.
>>  (eprintf "drracket-link.rkt = ~s\n"
>>           (resolved-module-path-name
>>            (variable-reference->resolved-module-path
>>             (#%variable-reference))))
> wait... isn't that part of the error message I attached earlier?  Viz:
> namespace-attach-module: unknown module (in the source namespace): #<resolved-module-path:"/Users/clements/clements/planet-collects/rsound/private/drracket-link.rkt">

No, that's based on the absolute module path you passed to 
namespace-attach module.

What I'm wondering about is, when you use the relative require, what 
does the module think its resolved module path is. That's what the 
expression above is designed to show.


Posted on the dev mailing list.