Re: EWidgetMessageTypes

From: Sean Kelly (kelly@charm.physics.ucla.edu)
Date: Sun Jun 27 1999 - 20:35:42 MEST


Hi Fons,

thanks for the response.  I'm guess I'm still worried about casting an
integer outside the range of an Enum, i.e. if the max val in an enum is 8
then the range of values you can cast an int to is 0:15.  According to
Stroustrup's book casting and int outside this range is undefined.  If you
set kC_MSGMAX = 1024 then the compiler would be forced to allocate more
bits to the enum and users could safely use messages in the range
[1000,2046]

cheers

Sean

_____________________________________________

Sean Kelly
Dept. of Physics
University of California Los Angeles
office tel. (310)-825-6035
fax (310)-206-4397 
voice mail (310)-259-3747
_____________________________________________

On Sun, 27 Jun 1999, Fons Rademakers wrote:

> Hi Sean,
> 
>    the EWidgetMessageTypes enum is just to provide nice nmemonics for the
> message types. The kC_MSGMAX id was not used and I've removed it from
> the enum. Casting to the EWidgetMessageTypes enum is ok. However to prevent
> any clash with future system widgets I propose that user defined message
> types are >1000. For sub-messages the range is always 1-255.
> 
> I've added this user message type requirement (>1000) to the documentation
> (in the new header WidgetMessageTypes.h).
> 
> 
> Cheers, Fons.
> 
> 
> > 
> > Hi Rooters
> > 
> > To take advantage of MK_MSG I used statements such as,
> > 
> > #define   M_NEW_1DHISTO      ((EWidgetMessageTypes) 9)
> > 
> > Casting an integer outside the range of the enumeration worked (at least
> > on my platform) but I gather this is not the way to go.
> > 
> > The comment in the source (TGWidget.h)
> > 
> > //--- Widget messages and submessages
> > //    (sub messages must be in the range 1-255)
> > //    (these should be on a separate include file)
> > 
> > seems to indicate that sub-messages can be valued up to 255 but
> > the enumeration has a max val of 8 ?
> > 
> > thanks for any help
> > 
> > 	Sean 
> > _____________________________________________
> > 
> > Sean Kelly
> > Dept. of Physics
> > University of California Los Angeles
> > office tel. (310)-825-6035
> > fax (310)-206-4397 
> > voice mail (310)-259-3747
> > _____________________________________________
> > 
> > 
> 
> 
> -- 
> Org:    CERN, European Laboratory for Particle Physics.
> Mail:   1211 Geneve 23, Switzerland
> E-Mail: Fons.Rademakers@cern.ch              Phone: +41 22 7679248
> WWW:    http://root.cern.ch/~rdm/            Fax:   +41 22 7677910
> 



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