On Thu, 23 Sep 2010, Graeme Geldenhuys wrote:
On 23 September 2010 09:46, Michael Van Canneyt wrote:
my FPC Language Reference docs with what you mentioned, or see if
Michael van Canneyt could add that info into the official docs so
others can benefit too.
What do you want added ? I haven't seen anything which isn't already
mentioned somehow in the docs ?
I'll re-read the docs covering array and dynamic arrays just to make
sure. What I think is missing, is the "gotcha" usages of arrays and
pointers to various array types. eg:
[ Snip: I'll see about what I can add to make it more clear ]
Like I said, I read the FPC lang ref docs regarding arrays, but the
above information was not immediately obvious to me. I'll re-read the
docs now to see if I maybe just missed that information (which could
be possible too).
Side note:
Even if the above is in the docs (maybe worded differently), this
gives me a reason to complete the DocView annotations support anyway,
so I can add extra info for when my brain is not working so well. :-)
Out of interest. Do you know if dynamic array elements are in sequence
(storage area in memory) too - like static arrays? So could I do the
Yes.
Perfect, using dynamic arrays will be easier (and cleaner
implementation) when I need to send an array to the C library.
As for freeing the array that the C API returned to me... I don't do
the freeing, I simply notify the C library when I am done using the
array, and the library does the freeing for me.
No. This you cannot do, since the pascal memory manager allocated the array,
it must also free it. The C memory manager has no idea about this
'memory'. You must manually do a SetLength(myarray,0);
Maybe you understood me wrong, or indeed there is something I need to
free myself. What I was referring to in the quoted text above, is when
the C API allocated the array, and I simply retrieved a pointer to
that array. In such cases I believe I don't need to do the freeing, I
simply tell the C API to do the freeing. In the case of Xlib, that is
done with the XFree() call.
Take care that in this case you should not use a dynamic array to refer to
the memory allocated by the C API:
Dynamic arrays are finalized at the end of a procedure, and since the Pascal
memory manager has no knowledge of the memory allocated by the C lib, things
will go horribly wrong when the dynamic array goes out of scope.
Michael.
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