Re: [Vala] Sorting a GLib.List<string>

[Didier 'Ptitjes' <ptitjes free fr>]

Hi Magnus,

Magnus Therning wrote:
> What function should I use to sort a list of strings to avoid the 
> compiler warning I get with strcmp:
>
>   ...
>   my_list.sort( strcmp );
>   ...
>
> Test.vala:60: warning: passing argument 2 of ‘g_list_sort’ from 
> incompatible pointer type
> /usr/include/glib-2.0/glib/glist.h:101: note: expected ‘GCompareFunc’ 
> but argument is of type ‘int (*)(const char *, const char *)’

You have to explicitly cast it to CompareFunc. Indeed, the GLib.strcmp 
is just a convenience binding around stdlib's strcmp, and they appear to 
not have the exact same signatures. IIRC those are:

int strcmp (void* a, void* b)
gint GCompareFunc (gconstpointer, gconstpointer)

However, I would suggest you to use libgee-0.5 which is expected to be 
(finally) released on Monday September 29, 2009 (or master from git).

Gee.List<G>.sort uses an efficient TimSort algorithm, and for free you get:
 * transparent uses of standard compare funcs for primitive, string and 
object types
 * possibility to make your classes inherit Comparable<G>
 * rid of equal functions at List construction time for primitive, 
string and object types

Best regards, Didier.