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Re: uniform-array-read!

From: Ludovic Courtès
Subject: Re: uniform-array-read!
Date: Tue, 31 Jan 2006 14:42:07 +0100
User-agent: Gnus/5.110004 (No Gnus v0.4) Emacs/21.4 (gnu/linux)


William Xu <address@hidden> writes:

> Is the following the correct way of using `uniform-array-read!'? Seems
> it simply hangs there.. 
>   (let ((ar (make-uniform-array #\nul length)))
>     (uniform-array-read! ar sockfd))

In your example, it can very well be hanging because there is nothing to
read from SOCKFD (e.g., it's making a blocking `read' system call

Using Guile 1.7:

  guile> (define a (make-uniform-array #\nul 10))
  guile> (uniform-array-read! a (open-input-string (string #\001 #\002 #\003)))
  guile> a
  #s8(1 2 3 32 51 10 -102 96 48 10)

IOW, it seems to work fine --- except that:

 1. The array is not properly initialized;

 2. The result is not a string as one would expect from the Guile 1.6
    manual[*] (in fact it could hardly be a string since internally
    strings may not contain null characters AFAIK).

So 1.7 is _not_ compatible with 1.6 in that respect.  I guess we need to
fix this.

In 1.7, `make-uniform-array' is deprecated and replaced by
`make-typed-array' (BTW, this deprecation is not currently documented in
the 1.7 manual):

  -- Scheme Procedure: make-typed-array type fill bound ...
  -- C Function: scm_make_typed_array (type, fill, bounds)
      Create and return an array that has as many dimensions as there are
      BOUNDs and (maybe) fill it with FILL.

Hope this helps,

[*] From node `Uniform Arrays':

      Unshared uniform arrays of characters with a single zero-based dimension
      are identical to strings:

           (make-uniform-array #\a 3) =>

      Unshared uniform arrays of booleans with a single zero-based dimension
      are identical to *Note bit-vectors: Bit Vectors.

           (make-uniform-array #t 3) =>

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