96 lines
2.6 KiB
Markdown
96 lines
2.6 KiB
Markdown
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Better exception declaration and use
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====================================
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A C++ exception class and macros with easy nested declaration and localisation
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data.
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The point of this system is to permits to easily add to exceptions instances
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some informations about _where_ (in the source code) the exceptions are thrown.
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It also ease declaration of new exception classes and their use.
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Example
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-------
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```cpp
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#include <iostream>
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#include <iomanip>
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#include <exceptions/exceptions.h>
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// Use this macro to build up your hierarchy of exceptions
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EXCEPTION( Exception, Existential_Observation );
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EXCEPTION( Existential_Observation, Buddhist_Observation );
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EXCEPTION( Buddhist_Observation, Zen_Observation );
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EXCEPTION( Existential_Observation, Pastafarism_Observation );
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int main()
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{
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try {
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double pi = 3.1415926535;
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// Use this macro to easily throw an exception with a dynamic message
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RAISE( Pastafarism_Observation, std::setprecision(3) << "Shit happens with " << pi << " noodly appendages" );
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} catch( Existential_Observation & e ) {
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std::cerr << e.what() << std::endl;
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}
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}
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```
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Will output:
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```
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[:~/code/exceptions] master* ± g++ example.cpp && ./a.out
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Shit happens with 3.14 noodly appendages (<Pastafarism_Observation> in main at example.cpp:18)
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```
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Explanations
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============
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Declaration
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-----------
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It permits a one-line declaration of new exceptions, derived from
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existing ones.
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Example:
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```cpp
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EXCEPTION( Exception, Existential_Observation );
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EXCEPTION( Existential_Observation, Pastafarism_Observation );
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```
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If you catch an `Existential_Observation`, you may thus catch an `Pastafarism_Observation` also.
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Note that the base `Exception` class derivate from `std::exception` and uses the standard `what` interface (more or less
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like `std::runtime_error` and `std::logical_error`).
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Location
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--------
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To add location information, it uses compilers macros that indicates the current function, file and line
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(`__FUNCTION__`, `__FILE__` and `__LINE__` for g++) and merge those information with the given description returned by
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the `what` standard method.
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You did not need to remember the name of those macros, they are available in the `E_INFOS` macro, that fit with the
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constructor of the `Exception` class.
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Example:
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```cpp
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throw Existential_Observation( "Shit happens", E_INFOS );
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```
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Use
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---
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It also provides a macro to easily throw an exception that permits to use
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dynamic streamed messages inline and without having to specify `E_INFOS`.
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Example:
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```cpp
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RAISE( Pastafarism_Observation, "Shit happens with " << 42 << " noodly appendages" );
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```
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