Questions tagged [exception-safety]
93 questions
49
votes
4 answers
What is wrong with "checking for self-assignment" and what does it mean?
In Herb Sutter's book Exceptional C++ (1999), he has words in item 10's solution:
"Exception-unsafe" and "poor design" go hand in hand. If a piece of code isn't exception-safe, that's generally okay and can simply be fixed. But if a piece of code…
Jimm Chen
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48
votes
14 answers
The simplest and neatest c++11 ScopeGuard
I'm attempting to write a simple ScopeGuard based on Alexandrescu concepts but with c++11 idioms.
namespace RAII
{
template< typename Lambda >
class ScopeGuard
{
mutable bool committed;
Lambda rollbackLambda;
…
lurscher
- 25,930
- 29
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31
votes
7 answers
Ensuring that Exceptions are always caught
Exceptions in C++ don't need to be caught (no compile time errors) by the calling function. So it's up to the developer's judgment whether to catch them using try/catch (unlike in Java).
Is there a way one can ensure that the exceptions thrown are…
sachin
- 1,141
- 2
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- 21
28
votes
2 answers
std::make_shared() change in C++17
In cppref, the following holds until C++17:
code such as f(std::shared_ptr(new int(42)), g()) can cause a
memory leak if g gets called after new int(42) and throws an
exception, while f(std::make_shared(42), g()) is safe, since
two…
Lingxi
- 14,579
- 2
- 37
- 93
27
votes
2 answers
Safety of std::unordered_map::merge()
While writing some code targeting C++17, I kind of hit a stumbling block determining the exception-safety of an operation merging two compatible std::unordered_maps. Per the current working draft, §26.2.7, table 91 reads, in part, regarding the…
Capital C
- 271
- 2
- 5
27
votes
3 answers
Where can I find all the exception guarantees for the Standard Containers and Algorithms?
Yes, I've looked at the C++ standards that I could find (or the drafts), but I'm not finding any comprehensive of the exception guarantees given by STL containers. All I can find are occasional sections with incomplete descriptions on some of the…
user541686
- 205,094
- 128
- 528
- 886
22
votes
2 answers
Are deferred functions called when calling log.Fatalln?
db, err := sql.Open("postgres", "…")
if err != nil {
log.Fatalln(err)
}
defer db.Close()
tpl, err := template.ParseGlob("")
if err != nil {
log.Fatalln(err)
}
If template.ParseGlob("") returns an error, is db.Close() still being called?
user142019
22
votes
1 answer
Is it safe to use emplace_back with a container of unique_ptrs?
Consider the following:
std::vector> ptrsToInts;
ptrsToInts.emplace_back(new int);
If reallocation occurs in the vector, and that fails (throwing std::bad_alloc), am I "safe" or will I leak an int?
C++11 23.3.6.5…
Billy ONeal
- 104,103
- 58
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- 552
20
votes
4 answers
Is there a C++ standard class to set a variable to a value at scope exit
Within the scope of a member function, I want to temporarly set a member variable to a certain value.
Then, when this function returns, I want to reset this member variable to a given known value.
To bo safe against exceptions and multiple returns,…
Didier Trosset
- 36,376
- 13
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- 122
20
votes
3 answers
Exception safety and make_unique
Just to clarify, using make_unique only adds exception safety when you have multiple allocations in an expression, not just one, correct? For example
void f(T*);
f(new T);
is perfectly exception safe (as far as allocations and stuff), while
void…
Kal
- 1,309
- 11
- 16
18
votes
1 answer
Exception-safety of C++ implicitly generated assignment operator
My understanding is that C++ implicitly generated assignment operator does a member-wise copy (this seems confirmed also by this answer). But, if during a member copy an exception is thrown (e.g. because a resource for that member can't be…
Mr.C64
- 41,637
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12
votes
2 answers
Sink arguments and move semantics for functions that can fail (strong exception safety)
I have a function that operates on a big chunk of data passed in as a sink argument. My BigData type is already C++11-aware and comes with fully functional move constructor and move assignment implementations, so I can get away without having to…
ComicSansMS
- 51,484
- 14
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10
votes
1 answer
Memory leak during unordered_map::insert KeyEqual exception with GCC - breaking the strong exception safety guarantee?
I'm using GCC 7.3.1, but also tested on coliru, which I believe is version 9.2.0. Build with the following:
g++ -fsanitize=address -fno-omit-frame-pointer rai.cpp
Here's rai.cpp:
#include
#include
int main()
{
try
…
Rai
- 1,328
- 11
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10
votes
1 answer
How exception-safe is std::tie?
std::tie returns a tuple of references, so you can do the following:
int foo, bar, baz;
std::tie(foo, bar, baz) = std::make_tuple(1, 2, 3);
This is similar to foo, bar, baz = (1, 2, 3) in Python.
What is supposed to happen if one of the assignments…
user142019
10
votes
3 answers
Exception safety regarding swap() operation - what's so wrong with that?
I keep reading that swap() operation, like this for example:
template
void swap (T &a, T &b)
{
T temp (a);
a = b;
b = temp;
}
is problematic when we are dealing with Exception-safety.
What's so wrong with it?
Furthermore, how can…
JAN
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