idiom.
Most LLVM tool code exits immediately when an error is encountered and prints an
error message to stderr. The ExitOnError class supports this by providing two
call operators - one for Errors, and one for Expected<T>s. Calls to code that
can return Errors (or Expected<T>s) can use these calls to bail out on error,
and otherwise continue as if the operation had succeeded. E.g.
Error foo();
Expected<int> bar();
int main(int argc, char *argv[]) {
ExitOnError ExitOnErr;
ExitOnErr.setBanner(std::string("Error in ") + argv[0] + ":");
// Exit if foo returns an error. No need to manually check error return.
ExitOnErr(foo());
// Exit if bar returns an error, otherwise unwrap the contained int and
// continue.
int X = ExitOnErr(bar());
// ...
return 0;
}
llvm-svn: 263749
This patch introduces the Error classs for lightweight, structured,
recoverable error handling. It includes utilities for creating, manipulating
and handling errors. The scheme is similar to exceptions, in that errors are
described with user-defined types. Unlike exceptions however, errors are
represented as ordinary return types in the API (similar to the way
std::error_code is used).
For usage notes see the LLVM programmer's manual, and the Error.h header.
Usage examples can be found in unittests/Support/ErrorTest.cpp.
Many thanks to David Blaikie, Mehdi Amini, Kevin Enderby and others on the
llvm-dev and llvm-commits lists for lots of discussion and review.
llvm-svn: 263609
Lang Hames