Questions tagged [exception-safety]
93 questions
9
votes
1 answer
C++: why this simple Scope Guard works?
Every looked at scope guard so far has a guard boolean variable. For example, see this discussion:
The simplest and neatest c++11 ScopeGuard
But a simple guard works (gcc 4.9, clang 3.6.0):
template
struct finally_t : public C {
…
funny_falcon
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8
votes
2 answers
Locking a mutex in a destructor in C++11
I have some code which need to be thread safe and exception safe. The code below is a very simplified version of my problem :
#include
#include
std::mutex mutex;
int n=0;
class Counter{
public:
Counter(){
…
Arnaud
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5
votes
1 answer
Implementing std::vector::push_back strong exception safety
I'm implementing my own vector based on post-2018 San Diego draft (N4791) and have some questions regarding implementing strong exception safety.
Here is some code:
template
void Vector::push_back(const…
user3624760
5
votes
4 answers
C++ exceptions vs. C# exceptions
In an old blog entry titled Cleaner, more elegant, and harder to recognize, the author states:
In C++ it's not quite so bad because C++ exceptions are raised only at specific points during execution. In C#, exceptions can be raised at any…
fredoverflow
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4
votes
1 answer
state of std::vector after std::bad_alloc
I'm trying to find a online reference to see the exception safety of several std containers.
In the case of std::vector, Does it keep the state previous to the push_back call? I would presume the vector has all its objects still valid (no…
lurscher
- 25,930
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4
votes
2 answers
RAII in Objective-C pattern?
I find myself writing code like this to achieve exception safe code:
Container* container = [Container new];
@try {
while(someCondition) {
ElementType* value = [someObject createObjectFromStorage];
[container add:value]; //…
Jörgen Sigvardsson
- 4,839
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4
votes
3 answers
Is it OK to have a throwing swap member-implementation?
The general guideline when writing classes (using the copy-and-swap idiom) is to provide a non throwing swap member function. (Effective C++, 3rd edition, Item 25 and other resources)
However, what if I cannot provide the nothrow guarantee because…
Martin Ba
- 37,187
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4
votes
2 answers
Should I use `std::uncaught_exceptions()` to decide whether to throw an exception from my dtor?
I have a class whose ctor makes a driver call, and whose dtor makes the matching terminating/release driver call. Those calls can fail. The problem is naturally with the dtor.
I am naturally aware of the common wisdom of avoiding exceptions in…
einpoklum
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4
votes
4 answers
How do I design a function with a strong exception guarantee?
I have a function which I would like to have the strong exception guarantee:
class X {
/* Fields and stuff */
void some_function() {
vector1.push_back(/*...*/); // May Throw
vector2.push_back(/*...*/); // May Throw
…
SomeProgrammer
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4
votes
2 answers
Is this item from Effective Modern C++ still up to date?
p.146 of effective modern C++ :
void processWidget(std::shared_ptr spw, int priority);
void cusDel(Widget *ptr);//a custom deleter
This was an unsafe call prior to C++17 :
processWidget(std::shared_ptr(new Widget, cusDel),…
user
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4
votes
2 answers
How to prevent Buffer overflow / array overflow?
I was recently writing code for a custom serial communication protocol. What I did was, I used a part(8/16 bit) of the receiving data to denote how big the frame size is. Based on this data I expect that no of data to follow. I use Crc to accept or…
seetharaman
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4
votes
2 answers
Is std::list's multi-element inserts strongly exception-safe?
In item 17 of exceptional c++, I find this:
First, for all containers, multi-element inserts ("iterator range"
inserts) are never strongly exception-safe.
but in item 1 of effective STL, I find this:
If you need transactional semantics for…
guorongfei
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4
votes
1 answer
Exceptionsafety of make_unique: Why is f(new T) exception safe
I have been reading GOTW102, and wonder, why make_unique is more exception safe than the other cases, or in detail why f(new T(...)) is more exception safe than f(new T1(...), new T2(...)).
The make_unique implementation from the blog…
ted
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4
votes
1 answer
Exception safety with shared_ptr's constructor
In Effective C++ 3/E, I read this:
This is exception unsafe code:
class Test { };
void foo(const std::shared_ptr &ptr, int i);
int bar();
...
foo(std::shared_ptr(new Test), bar());
Because compiler can implement like this:
run new…
ikh
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4
votes
3 answers
How can an implementation guarantee that copy constructor of an iterator is no throw?
Clause 23.2.1.10 of C++11 standard says that
"no copy ctor of a returned iterator throws an exception"
Does this basically state that is it possible for a copy ctor of an iterator not to throw even a bad_alloc presumably (leaving the case where…
Gmt
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