Re: The life of a Grob

[Joe Neeman]

On Sat, 2006-09-23 at 13:47 +0200, Han-Wen Nienhuys wrote:
> Joe Neeman wrote:
> > On Sat, 2006-09-16 at 16:29 +0200, Han-Wen Nienhuys wrote:
> >> Joe Neeman wrote:
> >>> Understanding the LilyPond source often boils down to figuring out what
> >>> is happening to the Grobs. Where (and why) are they being created,
> >>> modified and destroyed? I've spent many hours tracing Lily through a
> >>> debugger and it is mind-blowingly tedious.
> >>>
> >>> So I quickly hacked a few things together and came up with something a
> >>> bit better. I added hooks into internal_grob_set_property and
> >>> make_grob_from_properties. You can register a scheme callback which will
> >>> get called whenever a Grob is modified or created. The scheme callback
> >>> will receive the file and line numbers in the C++ source where the call
> >>> was made. This can help you to trace cause and effect through the C++
> >>> source.
> >> Of course, having written much of the code myself, I don't need it, but 
> >> this is extremely cool!
> >>
> >> Some comments:
> >>
> >> * can you add another macro layer, so __LINE__ and __FILE__ aren't 
> >> sprinkled around in the code? For good measure, you could also add 
> >> __FUNCTION__ .
> > 
> > This is done. I've removed all direct calls to internal_foo. I also
> > cleaned up make_{item,paper_column,spanner}.
> > 
> >> * similarly, can you add macro layering, so that passing around line 
> >> numbers/file  names is entirely optional, and doesn't happen for a 
> >> -DNDEBUG build?
> > 
> > I've done this, too but I'm not sure about it -- some of the ifndefs
> > start to inhibit readability.
> > 
> > What if I get rid of just the ifndef'ed prototypes? Ie. the line
> > numbers, etc will get passed around, but they won't get used when NDEBUG
> > is defined.
> 
> that's an option. I'm worrying a bit about performance though. 
> get_property() and friends take  a lot of time (10 to 20% of overall 
> execution time).
> 
> please apply after successful "make web".

But would passing an extra 3 (compile-time constant) variables make any
difference? In any case, I've committed it with all the ifndefs, and if
things get too ugly, they can always be taken out.