> If you don't mind requiring that `name` be supplied first, you could > simply pass the remaining args through unchanged:
For my purposes that's fine, though it's still a bit of a cheat. And cheating may not be an option next time ... > Separately, I think one gotcha with your original macro will be if you > use it more than once? I think you need to provide a fresh id to each > define-runtime-path, like so: I thought that would be the case too, though it does work without `generate-temporaries`. (Looking at the macro expansion, it seems each time the macro operates, it assigns a unique subscript to each "rp" identifier so they don't collide). But I can't tell if that's just lucky behavior. `Generate-temporaries` is clearly the right way to do things. Thanks. On Sep 7, 2014, at 2:11 PM, Greg Hendershott <[email protected]> wrote: > If you don't mind requiring that `name` be supplied first, you could > simply pass the remaining args through unchanged: > > (define-syntax (image/rp stx) > (syntax-case stx () > [(_ name xs ...) > #'(begin > (define-runtime-path id name) > (image id xs ...))])) > > It's not ideal because normally it should be fine to put the keyword > arguments before the positional one. However if this is just a private > helper macro it's probably fine. If you wanted, you could have the > macro sanity check that `name` is not keyword? -- or more to the > point, that it _is_ identifier?. (That kind of stuff is nice to > declare with syntax-parse; it make a nice error message for you.) > > > Separately, I think one gotcha with your original macro will be if you > use it more than once? I think you need to provide a fresh id to each > define-runtime-path, like so: > > (define-syntax (image/rp stx) > (syntax-case stx () > [(_ name xs ...) > (with-syntax ([id (generate-temporary)]) > #'(begin > (define-runtime-path id name) > (image id xs ...)))])) > > > On Sun, Sep 7, 2014 at 2:18 PM, Matthew Butterick <[email protected]> wrote: >> I made a rudimentary helper macro called `image/rp` that upgrades a relative >> path-string into a runtime path: >> >> (define-syntax (image/rp stx) >> (syntax-case stx () >> [(_ name) #'(image/rp name 1.0)] >> [(_ name scale) #'(begin >> (define-runtime-path rp name) >> (image rp #:scale scale))])) >> >> Of course, the problem is that it disregards the interface for `image`, >> which includes keyword arguments. >> >> Is there a standard idiom for matching keyword arguments with `syntax-case` >> ... >> >> 1) To capture all keyword arguments and pass them through unaltered? >> 2) To unpack keyword arguments, alter them, and reapply them? >> >> >> >> On Sep 1, 2014, at 9:59 PM, Matthew Flatt <[email protected]> wrote: >> >>> I think the docs are wrong. While `raco setup` does set the current >>> directory, `scribble` does not. >>> >>> It's better to use `define-runtime-path` instead of relying on the >>> current directory, since that composes better. >>> >>> At Mon, 1 Sep 2014 18:20:05 -0700, Matthew Butterick wrote: >>>> I am confused by this statement in the docs vs. the actual behavior: >>>> >>>> The docs for `image` say that "If path is a relative path, it is relative >>>> to >>>> the current directory, which is set by `raco setup` and `scribble` to the >>>> directory of the main document file." (I'm using `image` as an example but >>>> I've >>>> seen the same problem with CSS files.) >>>> >>>> Suppose I have a project set up like this: >>>> >>>> /project >>>> /scribblings >>>> main.scrbl >>>> sample.gif >>>> >>>> And "main.scrbl" contains this: >>>> >>>> #lang scribble/manual >>>> @image["sample.gif"] >>>> >>>> If I do this: >>>>> cd project >>>>> cd scribblings >>>>> scribble main.html >>>> >>>> The HTML will render fine. >>>> >>>> But if I do this: >>>> >>>>> cd project >>>>> scribble --dest-name doc scribblings/main.scrbl >>>> >>>> I'll get this error: >>>> >>>> open-input-file: cannot open input file >>>> path: /project/sample.gif >>>> >>>> Thus, the relative path "sample.gif" is being resolved relative to the >>>> directory where I invoke the `scribble` command, not the "directory of the >>>> main >>>> document file", which in both cases seems like it should be >>>> /project/scribblings (i.e., the directory containing "main.scrbl"). >>>> >>>> What am I misunderstanding? >>>> >>>> >>>> >>>> >>>> >>>> >>>> [1] >>>> http://docs.racket-lang.org/scribble/base.html?q=image#%28def._%28%28lib._scribb >>>> le%2Fbase..rkt%29._image%29%29____________________ >>>> Racket Users list: >>>> http://lists.racket-lang.org/users >> >> >> ____________________ >> Racket Users list: >> http://lists.racket-lang.org/users ____________________ Racket Users list: http://lists.racket-lang.org/users
