mirror of
https://gitlab.freedesktop.org/gstreamer/gstreamer.git
synced 2024-12-22 08:17:01 +00:00
51 lines
1.6 KiB
Markdown
51 lines
1.6 KiB
Markdown
# Ownership of dynamic objects
|
||
|
||
Any object-oriented system or language that doesn’t have automatic
|
||
garbage collection has many potential pitfalls as far as pointers
|
||
go. Therefore, some standards must be adhered to as far as who owns
|
||
what.
|
||
|
||
## Strings
|
||
|
||
Arguments passed into a function are owned by the caller, and the
|
||
function will make a copy of the string for its own internal use. The
|
||
string should be `const gchar *`. Strings returned from a function are
|
||
always a copy of the original and should be freed after usage by the
|
||
caller.
|
||
|
||
ex:
|
||
|
||
``` c
|
||
name = gst_element_get_name (element); /* copy of name is made */
|
||
.. use name ..
|
||
g_free (name); /* free after usage */
|
||
```
|
||
|
||
## Objects
|
||
|
||
Objects passed into a function are owned by the caller, any additional
|
||
reference held to the object after leaving the function should increase
|
||
its refcount.
|
||
|
||
Objects returned from a function are owned by the caller. This means
|
||
that the caller should `_free()` or `_unref()` the objects after usage.
|
||
|
||
ex:
|
||
|
||
``` c
|
||
peer = gst_pad_get_peer (pad); /* peer with increased refcount */
|
||
if (peer) {
|
||
.. use peer ..
|
||
gst_object_unref (GST_OBJECT (peer)); /* unref peer after usage */
|
||
}
|
||
```
|
||
|
||
## Iterators
|
||
|
||
When retrieving multiple objects from an object, an iterator should be
|
||
used. The iterator allows you to access the objects one after another
|
||
while making sure that the retrieved set of objects remains consistent.
|
||
|
||
Each object retrieved from an iterator has its refcount increased or is
|
||
a copy of the original. In any case the object should be unreffed or
|
||
freed after usage.
|