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Difference between revisions of "cpp/error/nested exception"

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< cpp‎ | error
(→‎Member functions: fix links)
(example moved to template)
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===Example===
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{{cpp/error/exception/nested_exception_example}}
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{{example cpp
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| Demonstrates construction and recursion through a nested exception object
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| code=
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#include <iostream>
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#include <stdexcept>
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#include <exception>
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#include <string>
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#include <fstream>
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// prints the explanatory string of an exception.
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// if the exception is nested, recurses to print the explanatory of the exception it holds
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void print_exception(const std::exception& e, int level =  0)
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{
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    std::cerr << std::string(level, ' ') << "exception: " << e.what() << '\n';
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    try {
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        std::rethrow_if_nested(e);
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    } catch(const std::exception& e) {
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        print_exception(e, level+1);
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    } catch(...) {}
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}
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// sample function that catches an exception and wraps it in a nested exception
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void open_file(const std::string& s)
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{
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    try {
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        std::ifstream file(s);
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        file.exceptions(std::ios_base::failbit);
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    } catch(...) {
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        std::throw_with_nested( std::runtime_error("Couldn't open " + s) );
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    }
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}
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// sample function that catches an exception and wraps it in a nested exception
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void run()
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{
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    try {
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        open_file("nonexistent.file");
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    } catch(...) {
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        std::throw_with_nested( std::runtime_error("run() failed") );
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    }
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}
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// runs the sample function above and prints the caught exception
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int main()
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{
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    try {
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        run();
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    } catch(const std::exception& e) {
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        print_exception(e);
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    }
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}
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| output=
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exception: run() failed
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exception: Couldn't open nonexistent.file
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  exception: basic_ios::clear
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}}
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===See also===
 
===See also===

Revision as of 17:50, 26 March 2012

Template:cpp/error/sidebar

Defined in header <exception>
class nested_exception;
 (since C++11)

std::nested_exceptions is a polymorphic mixin class which can capture and store the current exception, making it possible to nest exceptions of arbitrary types within each other.

Member functions

 constructs a nested_exception
(public member function of Template:cpp/error/exception/nested exception/title)
[virtual]
 destructs a nested exception
(virtual public member function of Template:cpp/error/exception/nested exception/title)
replaces the contents of a nested_exception
(public member function of Template:cpp/error/exception/nested exception/title)
throws the stored exception
(public member function of Template:cpp/error/exception/nested exception/title)
obtains a pointer to the stored exception
(public member function of Template:cpp/error/exception/nested exception/title)

Template:cpp/error/exception/nested exception example

See also

Template:cpp/error/exception/dcl list exception ptr
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