Re: Style convention question

[Mark Mielke <mark mark mielke cc>]

On Fri, Mar 09, 2001 at 05:58:01PM +0100, Sebastian Wilhelmi wrote:
> >         Why does Glib do this:
> > typedef struct _GFoo GFoo;
> > struct _GFoo {
> >         /* [...] */
> > };
> >         ...instead of the more compact
> > typedef struct {
> >         /* [...] */
> > } GFoo;
> Not being the definite source for that information, I think that is because
> sometimes "GFoo*" is used without "struct _GFoo" being declared (for opaque
> structs). For the other structs it's just consistency.

The second uses an anonymously defined struct, and generates warnings
with several compilers.


    struct { a, b, c }    is not necessarily:  struct { a, b, c }

whereas:

    struct abc            _is_:                struct abc


A typedef can be considered more of an "alias" for most compilers.
Consider:

    /* The '_' isn't strictly necessary, and the typedef can be left
     * out if C++ is being used to perform the compile.
     */

    #ifndef __cplusplus
    typedef Object struct Object;
    #endif

    struct Object {
        ...
    };

    int func (Object o) {
    {
       ...
    }

    ...
    struct Object o1;
    Object o2;
    struct { same_fields_as_struct_Object } o3;

    func(o1);   /* Legal */
    func(o2);   /* Legal */
    func(o3);   /* Illegal */



mark

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