[plt-scheme] reading a whole file

From: Stephen De Gabrielle (s.degabrielle at cs.ucl.ac.uk)
Date: Tue Nov 4 10:04:01 EST 2008

Wow - thanks for all the good advice,

I'm guessing that (port->string [input-port]) in (planet "port.ss"
("schematics" "port.plt" 1 2))  is similar to the method below.

I asked the question - so I'll copy the answer into the cookbook.

I understand the point about operating on files, but I feel this is
the special case of large numbers of small files, read only, and at
least 2gb RAM to work with. I may be wrong...



On Tue, Nov 4, 2008 at 2:46 PM, Robby Findler <robby at cs.uchicago.edu> wrote:
> With a reasonable filesystem (I'm not sure if Windows counts as sane
> in this regard, but mac os x and linux's both do I believe), this will
> work and not be subject to race conditions (all of the heavy lifting
> is in copy-port):
> #lang scheme
> (require scheme/port)
> (define (file->string f)
>  (let ([sp (open-output-string)])
>    (call-with-input-file f
>      (λ (fp) (copy-port fp sp)))
>    (get-output-string sp)))
> but I do not recommend reading files into strings. Instead, it is much
> better to just operate on the port if you possibly can.
> Probably I or others can help if you're not sure how to write whatever
> function you wanted directly on the port instead of on the string.
> Robby
> On Tue, Nov 4, 2008 at 9:42 AM, Shriram Krishnamurthi <sk at cs.brown.edu> wrote:
>> The Cookbook version has a slight non-atomicity problem (the file size
>> may change between the FILE-SIZE and the READ-STRING).  I don't know
>> quite how that works out in the version Veer posted (presumably the
>> same problem, because FILE-SIZE is being called on the file*name*, not
>> on the port descriptor).  I guess file operation atomicity is
>> OS-specific anyway.
>> Shriram
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