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List:       racket-dev
Subject:    [racket-dev] Should BSL signal an error on (require ...) in an unsaved buffer?
From:       clements () brinckerhoff ! org (John Clements)
Date:       2011-06-28 0:59:12
Message-ID: 769C5C26-E6E6-4563-9021-1EF609DA2106 () brinckerhoff ! org
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On Jun 27, 2011, at 5:47 PM, Robby Findler wrote:

> On Tue, Jun 28, 2011 at 8:41 AM, John Clements
> <clements at brinckerhoff.org> wrote:
> > 
> > On Jun 27, 2011, at 5:28 PM, Robby Findler wrote:
> > 
> > > On Tue, Jun 28, 2011 at 8:19 AM, John Clements
> > > <clements at brinckerhoff.org> wrote:
> > > > 
> > > > On Jun 27, 2011, at 5:10 PM, Robby Findler wrote:
> > > > 
> > > > > On Tue, Jun 28, 2011 at 7:52 AM, John Clements
> > > > > <clements at brinckerhoff.org> wrote:
> > > > > > 
> > > > > > On Jun 27, 2011, at 4:45 PM, Robby Findler wrote:
> > > > > > 
> > > > > > > We're talking about relative requires only, right?
> > > > > > > 
> > > > > > > How are you proposing to signal the error?
> > > > > > 
> > > > > > My guess about how this works--correct me if I'm wrong--is that for \
> > > > > > unsaved buffers, DrR sets a parameter such that the expanded code has the \
> > > > > > current directory as (uh, part of?) the syntax-source of the expanded \
> > > > > > source.  I'm guessing that I'm not right, or it would be as simple as \
> > > > > > disabling this for programs written in BSL et al.
> > > > > 
> > > > > DrRacket does indeed set current-directory and could instead signal an
> > > > > error instead of setting it. That would mean no unsaved file would
> > > > > run, however. Is that really desired?
> > > > 
> > > > Would it not be possible to set the syntax-source in such a way that relative \
> > > > requires would fail? We may be out of DrR and into just plain R here.
> > > 
> > > Yes, we have to be, I'm pretty sure.
> > > 
> > > > Indeed, I would be happy if buffers without a recorded save location couldn't \
> > > > make relative requires in *any* language level, though I realize that such a \
> > > > change would be more likely to have repercussions elsewhere.
> > > 
> > > I think that would probably require a new parameter that controls
> > > where relative requires are relative to being exported and allowing it
> > > to have a value that says "no relative requires allowed".
> > > (current-load-relative-directory is maybe already this, without the
> > > extra functionality, maybe?)
> > > 
> > > > I suppose there could be situations where users dynamically create syntax \
> > > > objects and set the current directory rather than setting the syntax-source \
> > > > of the objects, though that doesn't sound like the most robust way to write \
> > > > the code.
> > > 
> > > I don't understand this comment.
> > > 
> > > (I believe that the source field of a syntax objects is not involved
> > > in resolving relative requires.)
> > 
> > Ah! I understand better now.
> > 
> > Okay, out of the realm of how-things-should-be and into the realm of \
> > how-things-are; you write that DrR sets 'current-directory'.  Is there some \
> > reason to set 'current-directory' rather than 'current-load-relative-directory'? \
> > It looks to me like setting 'current-load-relative-directory' fixes the bug I'm \
> > tackling, but I want the stepper to accurately simulate DrR's behavior here.
> 
> Oh, I see that current-load-relative-directory can already be #f. I
> think that situation corresponds to "I'm not requiring anything", tho
> and, according to the docs, that parameter is set by the require
> machinery (not by drracket altho I didn't grep the sources to be
> sure). So again, I think we're stuck if all we change is drracket.
> 
> (I'm not sure, but I think that this is probably going to be more
> trouble than it is worth.)

Okey dokey. I've verified that setting "current-directory" has the desired effect, so \
I'm just going to set it to the result of the tab's "get-directory" before calling \
the expander to pull the exprs out of the defns window.  Let me know if this is \
obviously wrong.

Thanks!

John

(lost dev on intermediate response, sorry)


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