On Thu, Nov 21, 2013 at 11:07:21PM -0600, Maurice LeBrun wrote:
> On Thursday, November 21, 2013 at 22:53:02 (-0600) Maurice LeBrun writes:
> > I became curious reading this thread so I had a look -- apparently the
> answer
> > is in the code. From src/plcore.c:
> >
> > ...
> > void
> > plgDevs( const char ***p_menustr, const char ***p_devname, int *p_ndev )
> > {
> > plgdevlst( *p_menustr, *p_devname, p_ndev, -1 );
> > }
> >
> > static void
> > plgdevlst( const char **p_menustr, const char **p_devname, int *p_ndev,
> int type )
> > {
> > ...
> >
> > The pointers are dereferenced by the API calls to the implementing
> routine, so
> > are not needed. I probably meant to go back & fix that up eventually but
> > ended up forgetting all about it. :)
>
> I should add, I think I initially saw the problem as Andrew put it, that the
> array of char*'s was like a 2d array so in order to "return" it I needed to
> pass a pointer to a 2d array i.e. char***. But then realized I could skip
> that and just do pointer copies instead. Bleah.. give me a nice class foo&
> any day..
Maurice is right. We could make this simpler. The function is not part
of the common API so we could make a change now, although the function
has been available in C for quite a while so this may cause backwards
incompatibilities for some users.
With regard to the "const", this just means that the values won't be
modified, which is true since the function just returns an array of
pointers to the const device strings. This provides (some) safety to
prevent the user trying to modify them. They would need an explicit
cast to lose the const. This is my interpretation anyway. The use of
const with char arrays is complicated and one of those things I always
need to go away and check.
Andrew
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