const fcf::Exception&
nested(
size_t a_index)
const
Class: fcf::Exception
Package: fcfBasis
File:
bits/PartException/ExceptionDecl.hpp
(
link_to_the_declaration_in_the_file
)
Implementation file:
bits/PartException/Exception.hpp
(
link_to_the_implementation_in_the_file
)
Available from version: 1.0.1
Provides access to a specific nested exception within the exception hierarchy.
The nested method allows traversing the chain of causality in an fcf::Exception object. When an exception is created by wrapping another exception, the original exception and all its subsequent sub-exceptions are stored in an internal collection.
If the requested index does not exist, a reference to an empty fcf::Exception is returned.
Arguments
size_t a_index
- The zero-based index of the sub-exception to retrieve.
Result
const fcf::Exception&
- A reference to the sub-exception at the specified index.
Example: Traversing an exception hierarchy
Demonstrating how to create a chain of exceptions and traverse them using the nested method.
#define FCF_BASIS_IMPLEMENTATION
#include <fcfBasis/basis.hpp>
#include <iostream>
int main() {
try {
// 1. Create a bottom-level exception
fcf::Exception leaf("LeafError", "Leaf error occurred", __FILE__, __LINE__, "param");
// 2. Wrap it into a middle-level exception
fcf::Exception middle(leaf, "MiddleError", "Middle error occurred", __FILE__, __LINE__, "mid_param");
// 3. Wrap that into a top-level exception
fcf::Exception top(middle, "TopError", "Top error occurred", __FILE__, __LINE__, "top_param");
// 4. Inspect the hierarchy
std::cout << "Top exception message: " << top.message() << std::endl;
std::cout << "Number of sub-exceptions: " << top.nestedSize() << std::endl;
for (size_t i = 0; i < top.nestedSize(); ++i) {
// Accessing sub-exceptions via nested()
std::cout << " [" << i << "] " << top.nested(i).message() << std::endl;
}
} catch (const fcf::Exception& e) {
std::cout << "Caught: " << e.what() << std::endl;
}
return 0;
}
Output:
Top exception message: Top error occurred
Number of sub-exceptions: 2
[0] Middle error occurred
[1] Leaf error occurred
The nested method is essential for deep error inspection in complex systems where errors are wrapped as they propagate up the call stack.
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