C API tutorial
John (J5) Palmieri
johnp at redhat.com
Tue Nov 1 10:13:09 PST 2005
This is all really cool though I would rather a tutorial which utilized
filter functions and read_write_dispatch. The nice thing about doing it
that way is it is mostly interchangeable when using a real mainloop so
the mainloop becomes an implementation detail in the tutorial and not a
confusing "how should I structure my code?" detail. We can put sidebars
for tips on how to get messages without needing a filter function along
with the pitfalls in doing so.
On Tue, 2005-11-01 at 11:40 -0500, Havoc Pennington wrote:
> On Tue, 2005-11-01 at 12:27 +0000, Matthew Johnson wrote:
> > Having waded through the API docs myself I thought I ought to put my
> > example code up somewhere and write a short tutorial for anyone else who
> > is trying to use the C API. It's available here:
> > http://www.matthew.ath.cx/misc/dbus
> Cool! Some small suggestions,
> After you have finished with the bus you should close the
> The dbus_bus_get() bus is a shared connection within the process, so
> normally you would not close this connection. You do want to unref() the
> connection when you're done though.
> You can also use dbus_bus_get_private() to get your very own connection
> to the bus. In that case, you _do_ want to close it, since nobody else
> is using it.
> For interface names, the convention is foo.bar.CapitalLetters
> and for signal/method names just CapitalLetters.
> Half-tempted to enforce that in the code ;-)
> You check for out-of-memory failure on dbus_message_new but not for some
> other functions, like
> dbus_message_iter_append_basic, dbus_connection_send
> in a tutorial it's probably best to always check.
> yes it sucks but that's why the high-level bindings exist!
> When you read the method reply parameters, you are trusting that the
> other end sent the right thing; if you are trying to be secure/robust
> you would need to check the parameter types and be sure there are enough
> I would consider the loop with sleep(1) in it to be moderately bad in a
> real production app; dbus_connection_read_write_dispatch() would be
> better. If you want to use dbus_connection_pop(), then we might need to
> provide dbus_connection_read_write() I guess.
> You only unref() the msg if it is the expected method call, leaking it
> otherwise no?
> Anyway, cool, I'm just being nitpicky since it's example code people
> will be copying.
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