On 2011-08-17, at 13:03 , Phil Holmes wrote: > ----- Original Message ----- From: "Graham Percival" > <gra...@percival-music.ca> > To: "Carl Sorensen" <c_soren...@byu.edu> > Cc: "lilypond-devel Development" <lilypond-devel@gnu.org> > Sent: Wednesday, August 17, 2011 5:48 PM > Subject: Re: Uninitialized SCM variables > > >> On Wed, Aug 17, 2011 at 05:53:40AM -0600, Carl Sorensen wrote: >>> \On 8/16/11 10:25 PM, "Dan Eble" <d...@faithful.be> wrote: >>> >>> > Is there a reason that these variables in lily/profile.cc don't need to > >>> > be >>> > initialized? I don't have experience with guile, but it looks > >>> > dangerous. >>> >>> I guess the code in this section relies on the fact that the compiler will >>> initialize the unitialized value to zero. Do you believe that is a >>> problem? >> >> Is there a special rule that compilers will always initalize >> uninitialized scheme values to zero? Because I discovered a >> segfault just yesterday (in a different program) that was because >> of gcc [1] not initalizing a variable to 0. >> >> [1] or rather, the C standard does not specify that an >> uninitalized variable should be set to 0, so I do not blame gcc in >> the least; it was the programmer at fault. >> >> Cheers, >> - Graham > > In C-style languages, uninitialised variable are uninitialised and therefore > have an indeterminant value. Hence the danger of uninitialised pointers. > Some other languages do initialise them to 0 - visual basic is an example. In > more modern languages, (c# is one I'm familiar with) the compile fails if a > variable is not explicitly initialised.
Backing up… I believe the compiler will initialize the bits in the aforementioned variables to zero, but is zero a desirable default for SCM variables in general, and these in particular? It also just sank in that in another thread there was a statement that treating a SCM as a boolean is "very wrong". That would include a number of lines in ly_property_lookup_stats and note_property_access that use these variables. -- Dan _______________________________________________ lilypond-devel mailing list lilypond-devel@gnu.org https://lists.gnu.org/mailman/listinfo/lilypond-devel
