Re: Resolving EXC_BAD_INSTRUCTION (Where do I begin?)
Re: Resolving EXC_BAD_INSTRUCTION (Where do I begin?)
- Subject: Re: Resolving EXC_BAD_INSTRUCTION (Where do I begin?)
- From: Rua Haszard Morris <email@hidden>
- Date: Fri, 8 Sep 2006 09:19:22 +1200
Since noone told you, I'll chime in a week later:
Those warnings are "Effective C++" warnings, in the compiler settings
there's an "Effective C++" option; unchecking it will stop you seeing
those warnings.
Those particular warnings are probably not causing your bug but using
the debugger will point you to where things are going wrong..
cheers
Rua HM.
On 7/09/2006, at 3:47 PM, David A Rowland wrote:
At 10:36 PM -0400 9/6/06, Jeff Birac wrote:
On Sep 6, 2006, at 10:13 PM, David A Rowland wrote:
At 9:29 PM -0400 9/6/06, Jeff Birac wrote:
Clarification: I am employing the Open PowerPlant framework.
I am trying to minimize warnings, but some would lead to me
modifying code I am weary of touching (e.g., PowerPlant).
The (PowerPlant) code is riddled with warnings like:
warning: 'class LAttachment' has pointer data members
but does not override 'LAttachment(const LAttachment&)'
or 'operator=(const LAttachment&)'
warning: 'class LAttachable' has pointer data members
but does not override 'operator=(const LAttachable&)'
warning: 'LUndoer::mAction' should be initialized in the member
initialization list
Are these warnings really important or are they just there to
encourage "good practice"? If these are frivolous warning, then
how would I turn them off; I have not found any flag/switch/
preference to ignore such warnings.
I am reluctant to override the implicit any PowerPlant class'
Copy Constructor or Assignment Operator because their developers
may have a reason to allow (or rely on) the implicit
implementations.
They are there to enforce good practice, but they are not
frivolous. If you use the default copy or assign for an object
with pointer members, you will end with two objects having
pointers to the same structures. That could be disaster. For
example, if one of the copies goes out of existence and calls the
destructor, does the destructor free the objects pointed at? If
so, the remaining copy will point to invalid space. If not, where
is the pointed at thing freed?
The warning is telling you to think about it and perhaps use a
"deep" copy that copies not only the top object but also the
pointer destinations.
The warning on LUndoer is probably less serious. mAction must
have a default constructor, so you may be OK using it by default.
In fact, I'm surprised that's even a warning.
David
Thanks for the explanations...
They are there to enforce good practice, but they are not
frivolous. If you use the default copy or assign for an object
with pointer members, you will end with two objects having
pointers to the same structures. That could be disaster. For
example, if one of the copies goes out of existence and calls the
destructor, does the destructor free the objects pointed at? If
so, the remaining copy will point to invalid space. If not, where
is the pointed at thing freed?
LArray makes important use of such overrides to copy an array's
items into a separate Handle. But these warnings are kind of
cluttering up the build results. Is there a way to regulate these
(and other) warnings that do not have seemingly explicit build
options?
I'm a bit puzzled by the terminology. "override" usually means what
a function in a derived class does to a function of the same name
in a base class. "overload" means to give several functions in the
same class the same name but different signatures (parameters). The
warning messages say "override", but I think they mean "overload".
I don't know how to suppress those particular warnings. You could
write an explicit overloading assignment operator and copy
constructor, but I would rather live with the warning than clutter
the code.
You know the "Rule of Three"? At least that is what I call it. The
copy constructor, overloaded assignment operator and destructor
tend to occur together. That is, if you have one you often need the
others.
David
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