On Fri, 22 Jun 2012 15:55:12 +0100, Namespace <rswhi...@googlemail.com>
wrote:
If you have a null object you get an Access Violation without _any_
further information. That totally sucks.
It doesn't have to be that way.
A debug executable contains all sort of debugging information and a Just
In Time debugger can attach and make use of it to show the cause of the
access violation. Further, on both windows and various flavours of unix
you can get a stack dump, which can be loaded into a debugger and used to
locate the access violation.
For the JIT case it's all automated on windows if/when you have visual
studio installed, as soon as any application crashes a dialog appears and
you can attach/debug.
For the stack trace case I prefer using WinDbg where you can load the
stack trace, point it at the PDB (produced even on a release build) and
figure out where it crashed. If you have no PDB you can use a MAP file
and the stack offsets to determine the crash location.
Alternately, on windows you can call SetUnhandledExceptionFilter() to
install a handler to catch any/all unhandled "exceptions" including access
violations etc and then using the EXCEPTION_POINTERS ContextRecord member,
walk the stack and produce your own stack trace at the instant the
application "crashes" - I have some code which does this somewhere..
This last idea could automatically be built into exes produced by DMD so
they all crash and output a stack trace (perhaps only if built in debug
mode) and something similar can surely be done for unix. It's been a
while since I did any serious development in D so maybe automatic stack
traces already happen for some platforms?
And in my opinion a small "Ref!Type" is more informative for others who
use your code and you do not have to write assert(obj !is null); any
time in any method again.
It is nice to perform the assert/check once, then know from that point on
it cannot be null ever again - saves multiple asserts/checks and makes the
code cleaner in terms of having less "noise". I think types which cannot
be null are useful for that reason.
R
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