How about #lang racket (struct i (x) #:property prop:input-port 0) (define (an-i str) (i (open-input-string str))) (read (an-i "hello")) ;; yields 'hello
? On Sat, Apr 21, 2012 at 9:43 AM, Chad Albers <calb...@neomantic.com> wrote: > I was thinking more along the lines of: > > #lang racket > (struct i (x) #:property prop:input-port 0) > (define an-i (i "hello")) > (read an-i) ;; yields 'hello > > I know this doesn't work. IOW, the read operation actually has accesses to > a field inside the struct itself. If that's impossible, then I'm trying to > understand why structs could be treated like ports, but then the data in the > port doesn't really have access to the field-values in the struct. > > Thanks for your help, > -- > Chad > > > > > On Sat, Apr 21, 2012 at 12:35 PM, Matthias Felleisen <matth...@ccs.neu.edu> > wrote: >> >> >> On Apr 21, 2012, at 11:52 AM, Chad Albers wrote: >> >> Hi, >> >> I'm looking for an example of treating a struct like a port, which appears >> to be >> possible: http://docs.racket-lang.org/reference/portstructs.html?q=struct#(def._((quote._~23~25kernel)._prop~3ainput-port)) >> >> Apparently, this is a lot easier that using make-custom-port. What I >> would like to do is be able to declare a struct, set it's prop:input-port >> property, pass an instance of struct to a port procedure, like (read-bytes >> string-that-acts-like-port), and have the bytes sent to the read-bytes >> actually contain bytes that were stored in the fields of the struct itself. >> Is that possible, and is that the reason why one would treat a struct like >> a port? >> >> Thanks in advance for any examples, >> >> >> >> Do you mean something like this: >> >> #lang racket >> (struct i (x) #:property prop:input-port 0) >> (define an-i (i (open-input-string "hello world"))) >> (read an-i) ;; yields 'hello >> >> -- Matthias >> > > > ____________________ > Racket Users list: > http://lists.racket-lang.org/users > ____________________ Racket Users list: http://lists.racket-lang.org/users
