Re: Register group proposal

[Christopher Faylor <cgf at redhat dot com>]

On Mon, Feb 26, 2001 at 02:10:25PM +0100, Bernard Dautrevaux wrote:
>> -----Original Message-----
>> From: Nick Duffek [mailto:nsd@redhat.com]
>> Sent: Sunday, February 25, 2001 12:52 AM
>> To: Dautrevaux@microprocess.com
>> Cc: gdb@sources.redhat.com; insight@sources.redhat.com
>> Subject: RE: Register group proposal
>> 
>> 
>> On 23-Feb-2001, Bernard Dautrevaux wrote:
>> 
>> >Perhaps for avoiding an unneeded dependency, that would 
>> trigger superfluous
>> >recompiles of users of "abc.h" that do not need "xyz.h" if "xyz.h" is
>> >modified?
>> 
>> I agree that's a pain.  But prohibiting typedefs only avoids a small
>> subset of superfluous recompiles.  For example, changing a 
>> single macro in
>> gdbarch.h causes a massive rebuild.
>> 
>> Eventually, GCC probably will support header file compilation, which
>> probably will lead to fully-accurate dependency generation.  This will
>> eliminate superfluous recompiles.
>> 
>> In the meantime, the problem diminishes as hardware speedups 
>> outpace GCC
>> complexity.
>> 
>> However, humans won't ever get better at writing maintainable code or
>> understanding existing code.  Typedefs help us achieve both of those
>> goals.
>
>I must say that, although it's a bit shorter, I don't see a real advantage
>to define some interface type xxx for
>
>(1) typedef struct { ... } xxx;
>    void f(xxx*);
>
>and 
>
>(2) struct xxx;
>    void f(struct xxx*);

That works fine if xxx is a struct.  If, at some point, you have an
amazing idea that allows you to change all xxx's to "unsigned short"
you're stuck with a lot of editing.

cgf