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Merge branch 'as/api-allocation-doc' into maint
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* as/api-allocation-doc:
  api-allocation-growing.txt: encourage better variable naming
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gitster committed Jan 12, 2013
2 parents d0f9456 + 5062f9e commit ab60f2c
Showing 1 changed file with 8 additions and 6 deletions.
14 changes: 8 additions & 6 deletions Documentation/technical/api-allocation-growing.txt
Original file line number Diff line number Diff line change
Expand Up @@ -5,30 +5,32 @@ Dynamically growing an array using realloc() is error prone and boring.

Define your array with:

* a pointer (`ary`) that points at the array, initialized to `NULL`;
* 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 array, call `ALLOC_GROW(ary, n,
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 *ary;
sometype *item;
size_t nr;
size_t alloc

for (i = 0; i < nr; i++)
if (we like ary[i] already)
if (we like item[i] already)
return;

/* we did not like any existing one, so add one */
ALLOC_GROW(ary, nr + 1, alloc);
ary[nr++] = value you like;
ALLOC_GROW(item, nr + 1, alloc);
item[nr++] = value you like;
------------

You are responsible for updating the `nr` variable.

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