When I compile with clang, with -Wall -Wextra -Werror, I get an error saying, "unused variable 'r'". See online examle: https://wandbox.org/permlink/WE7dK6r5XCIxJ83f
IOW, one must use certain tools and options to get the protection.
If you're not using clang-tidy in your project, then you ought to start. I've managed to raise it on an ancient VS2008 codebase. It surprisingly works.
I think the library could, at least, assert in debug builds when a result or outcome is not inspected.
What does "not inspected" mean? In C and C++, historically when the programmer wishes to signal that they are intentionally throwing away a result, they write: ``` extern result<int> foo(); ... // I don't care if this succeeds or fails (void) foo(); ``` So okay, perhaps people should do that. But this is something people definitely do: ``` result<int> r = foo(); if(r) { x = r.value(); ... } ``` So now we need to make the explicit boolean operator become non-const in order to get it to set an internal flag so that the destructor can trip an assert on uninspected destruction. Now, I don't mind doing this, indeed I've left a free status bit for this sort of thing in the future. But are: - Non-const boolean operator - Non-const .has_value(), .has_error() etc - Non-const .value(), .error() etc observers ... a price worth paying for asserting an uninspected result, and this includes breaking the cast-to-void idiom? One could of course const cast off any const-ness, and flip the inspected bit on any form of inspection. But I personally think there is a much better way that what you propose Rob, and that's to use the construction hooks to log the construction of result/outcome in debug mode. This is what I do in my own code. See https://github.com/ned14/afio/blob/master/include/afio/v2.0/config.hpp#L321. This lets one detect, much more easily and without breaking behaviour semantics, unintentionally uninspected outcome/result. Niall -- ned Productions Limited Consulting http://www.nedproductions.biz/ http://ie.linkedin.com/in/nialldouglas/