On Thursday, 24 November 2016 at 14:06:40 UTC, Jonathan M Davis wrote:
Personally, I don't care much about having body as a usable symbol. It occasionally would be useful, but I can live without it. However, I _do_ find it very annoying that it's required for the function body when you have contracts. After all, it's not required when you write the function normally. Why should it be required when you have contracts on the function? The braces after the contracts are clearly for the function body. They couldn't be for anything else. The compiler always requires that the body be last after the in and out contracts, making the body keyword totally redundant. So, I've never understood why the body keyword was required. As far as I can tell, it fixes no ambiguity. It's just extra typing, and it makes contracts that much more verbose, which makes me that much more inclined to just not bother with them and put the assertions in the function body - particularly when I'm already of the opinion that they add no value outside of inheritance, because assertions at the beginning of the function take care of in contracts, and unit tests are really what covers the out contract case anyway (particularly since it's very rare that you can have a general test for the out contract rather than testing that specific input results in specific output).

- Jonathan M Davis


General tests of output are not so rare. The premise of property-based testing is being able to write such tests. Going over the functions in std.algorithm, for almost every one of them I can find a nontrivial property that any output should satisfy (for a valid input).

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