[nostalgia/developer-handbook] Update notes on error handling
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@ -162,18 +162,10 @@ classes in question.
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### Error Handling
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### Error Handling
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Exceptions are clean and nice in userland code running in environments with
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The GBA build has exceptions disabled.
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expansive system resources, but they are a bit of a pain in small bare metal
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Instead of throwing exceptions, all engine code must return ```ox::Error```s.
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environments.
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For the sake of consistency, try to stick to ```ox::Error``` in non-engine code
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The GBA build has them disabled.
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as well, but non-engine code is free to use exceptions when they make sense.
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Exceptions cause also the compiler to generate a great deal of extra code that
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inflates the size of the binary.
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The binary size bloat is often cited as one of the main reasons why many
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embedded developers prefer C to C++.
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Instead of throwing exceptions, all engine code must return Ox error codes.
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For the sake of consistency, try to stick to Ox error codes in non-engine code
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as well.
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Nostalgia and Ox both use ```ox::Error``` to report errors. ```ox::Error``` is
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Nostalgia and Ox both use ```ox::Error``` to report errors. ```ox::Error``` is
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a struct that has overloaded operators to behave like an integer error code,
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a struct that has overloaded operators to behave like an integer error code,
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plus some extra fields to enhance debuggability.
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plus some extra fields to enhance debuggability.
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@ -219,6 +211,22 @@ int caller2() {
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std::cout << val << '\n';
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std::cout << val << '\n';
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return 0;
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return 0;
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}
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}
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ox::Error caller3(int &i) {
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return foo(i).moveTo(i);
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}
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ox::Error caller4(int &i) {
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return foo(i).copyTo(i);
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}
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int caller5(int i) {
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return foo(i).unwrap(); // unwrap will kill the program if there is an error
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}
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int caller6(int i) {
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return foo(i).unwrapThrow(); // unwrap will throw if there is an error
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}
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```
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```
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Lastly, there are a few macros available to help in passing ```ox::Error```s
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Lastly, there are a few macros available to help in passing ```ox::Error```s
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@ -275,6 +283,7 @@ ox::Error engineCode() noexcept {
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return OxError(0);
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return OxError(0);
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}
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}
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```
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```
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Ox also has the ```oxRequire``` macro, which will initialize a value if there is no error, and return if there is.
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Ox also has the ```oxRequire``` macro, which will initialize a value if there is no error, and return if there is.
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It aims to somewhat emulate the ```?``` operator in Rust and Swift.
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It aims to somewhat emulate the ```?``` operator in Rust and Swift.
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@ -309,6 +318,9 @@ ox::Result<int> f2() noexcept {
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* ```oxRequireT``` - oxRequire Throw
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* ```oxRequireT``` - oxRequire Throw
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* ```oxRequireMT``` - oxRequire Mutable Throw
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* ```oxRequireMT``` - oxRequire Mutable Throw
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The throw variants of ```oxRequire``` are generally legacy code.
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```ox::Result::unwrapThrow``` is generally preferred now.
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### Logging and Output
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### Logging and Output
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Ox provides for logging and debug prints via the ```oxTrace```, ```oxDebug```, and ```oxError``` macros.
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Ox provides for logging and debug prints via the ```oxTrace```, ```oxDebug```, and ```oxError``` macros.
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