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git/Documentation/technical/api-allocation-growing.txt
Adam Spiers 5062f9e1b5 api-allocation-growing.txt: encourage better variable naming
The documentation for the ALLOC_GROW API implicitly encouraged
developers to use "ary" as the variable name for the array which is
dynamically grown.  However "ary" is an unusual abbreviation hardly
used anywhere else in the source tree, and it is also better to name
variables based on their contents not on their type.

Signed-off-by: Adam Spiers <git@adamspiers.org>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2013-01-06 12:57:56 -08:00

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allocation growing API
======================
Dynamically growing an array using realloc() is error prone and boring.
Define your array with:
* a pointer (`item`) that points at the array, initialized to `NULL`
(although please name the variable based on its contents, not on its
type);
* an integer variable (`alloc`) that keeps track of how big the current
allocation is, initialized to `0`;
* another integer variable (`nr`) to keep track of how many elements the
array currently has, initialized to `0`.
Then before adding `n`th element to the item, call `ALLOC_GROW(item, n,
alloc)`. This ensures that the array can hold at least `n` elements by
calling `realloc(3)` and adjusting `alloc` variable.
------------
sometype *item;
size_t nr;
size_t alloc
for (i = 0; i < nr; i++)
if (we like item[i] already)
return;
/* we did not like any existing one, so add one */
ALLOC_GROW(item, nr + 1, alloc);
item[nr++] = value you like;
------------
You are responsible for updating the `nr` variable.