Difference between revisions of "cpp/error/rethrow exception"
m (Use since= and until= params of {{ddcl}} template.) |
(P1675R2, pretending it's a DR.) |
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{{ddcl | header=exception | since=c++11 | | {{ddcl | header=exception | since=c++11 | | ||
| − | [[noreturn]] void rethrow_exception( std::exception_ptr p ) | + | [[noreturn]] void rethrow_exception( std::exception_ptr p ); |
}} | }} | ||
| − | Throws the previously captured exception object | + | Throws the previously captured exception object referred-to by the exception pointer {{tt|p}}, or a copy of that object. |
| + | |||
| + | It is unspecified whether a copy is made. If a copy is made, the storage for it is allocated in an unspecified way. | ||
| + | |||
| + | The behavior is undefined if {{tt|p}} is null. | ||
===Parameters=== | ===Parameters=== | ||
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===Return value=== | ===Return value=== | ||
(none) | (none) | ||
| + | |||
| + | ===Exceptions=== | ||
| + | The exception object referred-to by {{tt|p}} if no copy is made. | ||
| + | |||
| + | Otherwise, a copy of such exception object if the implementation successfully copied the exception object. | ||
| + | |||
| + | Otherwise, {{lc|std::bad_alloc}} or the exception thrown when copying the exception object, if allocation or copying fails, respectively. | ||
| + | |||
| + | ===Notes=== | ||
| + | Before {{wg21|P1675R2}}, {{tt|rethrow_exception}} was not allowed to copy the exception object, which is unimplementable on some platforms where exception objects are allocated on the stack. | ||
===Example=== | ===Example=== | ||
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{{dsc end}} | {{dsc end}} | ||
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Revision as of 03:12, 5 October 2021
| Defined in header <exception>
|
||
| [[noreturn]] void rethrow_exception( std::exception_ptr p ); |
(since C++11) | |
Throws the previously captured exception object referred-to by the exception pointer p, or a copy of that object.
It is unspecified whether a copy is made. If a copy is made, the storage for it is allocated in an unspecified way.
The behavior is undefined if p is null.
Contents |
Parameters
| p | - | non-null std::exception_ptr |
Return value
(none)
Exceptions
The exception object referred-to by p if no copy is made.
Otherwise, a copy of such exception object if the implementation successfully copied the exception object.
Otherwise, std::bad_alloc or the exception thrown when copying the exception object, if allocation or copying fails, respectively.
Notes
Before P1675R2, rethrow_exception was not allowed to copy the exception object, which is unimplementable on some platforms where exception objects are allocated on the stack.
Example
#include <exception> #include <iostream> #include <stdexcept> #include <string> void handle_eptr(std::exception_ptr eptr) // passing by value is OK { try { if (eptr) std::rethrow_exception(eptr); } catch(const std::exception& e) { std::cout << "Caught exception: '" << e.what() << "'\n"; } } int main() { std::exception_ptr eptr; try { [[maybe_unused]] char ch = std::string().at(1); // this generates a std::out_of_range } catch(...) { eptr = std::current_exception(); // capture } handle_eptr(eptr); } // destructor for std::out_of_range called here, when the eptr is destructed
Possible output:
Caught exception: 'basic_string::at: __n (which is 1) >= this->size() (which is 0)'
See also
| (C++11) |
shared pointer type for handling exception objects (typedef) |
| (C++11) |
captures the current exception in a std::exception_ptr (function) |
