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[Help-smalltalk] Re: Questions regarding CArray's
From: |
Paolo Bonzini |
Subject: |
[Help-smalltalk] Re: Questions regarding CArray's |
Date: |
Sun, 17 Oct 2010 10:55:46 +0200 |
User-agent: |
Mozilla/5.0 (X11; U; Linux x86_64; en-US; rv:1.9.2.9) Gecko/20100907 Fedora/3.1.3-1.fc13 Lightning/1.0b3pre Mnenhy/0.8.3 Thunderbird/3.1.3 |
On 10/16/2010 09:29 PM, Holger Hans Peter Freyther wrote:
Hi,
for a test case I would like to create a C Array.
I want to do something like:
(#(1 2 3) asByteArray asCObject: (CArrayCType from: #byte)) at: 0
so somehow my CArrayCType from: #byte is wrong. I should be able to find the
equivalent of<declaration: #( #(#name #array 3))>, if you lack the time I am
going to search more and will find the solution myself.
First of all, I should point out that #asCData: mallocs a block that
contains the _whole_ ByteArray.
Given this, I suggest you don't use CArrayCType, because a CObject is a
pointer and there is very little difference between:
1) a pointer to the first byte:
#[1 2 3] asCData: CByteType
2) a pointer to a 3-byte array:
#[1 2 3] asCData: (CByteType arrayType: 3)
I suggest using the former, for which I added a shortcut #asCData in
git, together with a similar shortcut for Strings: ('123' asCData) is
the same as ('123' asCData: CCharType).
Alternatively,
#[1 2 3] castTo: CByteType
creates the same thing, but backed by GC memory and with range checking.
Paolo