Re: [cdt-dev] [DSF] SessionType

[Vladimir Prus <vladimir@xxxxxxxxxxxxxxxx>]

On Thursday 08 July 2010 21:46:26 Marc Khouzam wrote:

> 
> > -----Original Message-----
> > From: Vladimir Prus [mailto:vladimir@xxxxxxxxxxxxxxxx] 
> > Sent: Thursday, July 08, 2010 12:39 PM
> > To: cdt-dev@xxxxxxxxxxx
> > Cc: Marc Khouzam
> > Subject: Re: [cdt-dev] [DSF] SessionType
> > 
> > On Thursday 08 July 2010 19:48:59 Marc Khouzam wrote:
> > 
> > > > -----Original Message-----
> > > > From: cdt-dev-bounces@xxxxxxxxxxx 
> > > > [mailto:cdt-dev-bounces@xxxxxxxxxxx] On Behalf Of Vladimir Prus
> > > > Sent: Thursday, July 08, 2010 6:17 AM
> > > > To: cdt-dev@xxxxxxxxxxx
> > > > Subject: [cdt-dev] [DSF] SessionType
> > > > 
> > > > 
> > > > Hi,
> > > > I'm looking at this definition from DSF:
> > > > 
> > > > 	public enum SessionType { LOCAL, REMOTE, CORE }
> > > 
> > > This is DSF-GDB specific.  (just to be fair to DSF :-))
> > > 
> > > > Unfortunately, despite quite some years of experience 
> > with gdb, I have
> > > > no idea what LOCAL and REMOTE means. 
> > > 
> > > REMOTE is when we connect to a gdbserver.
> > > LOCAL is when we use GDB on the host only.
> > 
> > And what if we connect to something that speaks gdb protocol, 
> > but is not a gdbserver?
> 
> Sure, but when I wrote this class, it was focused on the 
> functionality of DSF-GDB, which only supports gdbserver.
> 
> > > > Would it not be better to remove session type completely, and use
> > > > more detailed switches, like 'should run or continue to be used
> > > > when starting program', or 'run can be used to restart'.
> > > 
> > > If the problem is using -exec-run or -exec-continue, then the
> > > service which dispatches those commands can be overridden to handle
> > > the cases you want to deal with.
> > 
> > I am becoming somewhat concerned :-( You seem to suggest that
> > overridding a service -- that is, writing my own service class
> > and doing what I want -- is a sensible approach.
> 
> Yes.  That's DSF.
> 
> > However,
> > suppose I want to go this route. I'll derive from GDBControl_7_0
> 
> You don't even have to do that.  You can create your own service
> altogether.

Copy-pasting everything from GDBControl_7_0?

> > and what is the next step? startOrRestart method is pretty big,
> > and all I want to do is modify a single if condition inside it.
> > Clearly, copy-pasting it is not a good approach 
> 
> Yes, no one likes copy-pasting, but at some point it is
> unavoidable.  Your case requires to modify a single if condition,
> while someone else may need to modify some other tiny part
> of the same method.  At some point, we can't make every little
> behavior customizable.

I'd say there must be some balance here. Of course, it's not possible to
have every if statement become a method call. However, there are surely
some aspects that commonly need to be customized, and it seems reasonable
to provide extension interfaces how derived classes can customize them.
Are there so many such methods in GDBControl_7_0 that it makes sense to refuse
further additions, or you thin that -exec-run/-exec-continue difference is
not common enough?

Note that I'm not even asking about this specific method, but I wanted
to understand general design guidelines, and hope they are more detailed
that "create a custom service by copy-pasting".


Thanks,

-- 
Vladimir Prus
CodeSourcery
vladimir@xxxxxxxxxxxxxxxx
(650) 331-3385 x722