Aaron Faanes wrote:
On Sun, Sep 15, 2013 at 8:35 PM, Bill Spitzak <[email protected]
<mailto:[email protected]>> wrote:
On 09/15/2013 11:09 AM, Aaron Faanes wrote:
+/**
+ * Retrieves a pointer to the container of a given item.
+ *
+ * This macro allows conversion from a pointer to a contained
item to its
+ * container. This is useful if you have a contained item
like a wl_list,
+ * wl_listener, or wl_signal, and would like to retrieve the
struct that
+ * contains it.
+ *
+ * To demonstrate, given a wl_list contained by a wl_resource
I think you might want to add "in a member called 'link'" Without
this information it took a bit of puzzling to figure out exactly
what was going on.
Good point. I'll add that in.
+ *
+ * \code
+ * struct wl_list *some_link = ...;
I don't know if there are any real examples with a simpler object
but the doc is a little confusing by making the inner object a
complex one like wl_list. Is there an example where the member is
something simple like an int?
An int could certainly be used, though I'm not certain if there's any
real examples in the code, which is why I hesitate to use a primitive.
I thought that might be a problem. Using a real example is probably a
good idea.
What if the example was expanded slightly, like so:
\code
struct wl_container {
wl_list link;
...
};
struct wl_container container;
struct wl_list *item = &container.link;
struct wl_container *sample = NULL;
assert(&container == wl_container_of(item, sample, link);
\endcode
Does this make it clearer (without making it too verbose)?
No I think it iwas ok as long as the member name is given. Also I would
perfer an actual example of usage rather than an assert. I would guess
that most/all users pass the same pointer they are assigning to the
macro as the pointer-type argument?
ie keep "sample = wl_container_of(item, sample, link)"
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