On 27.12.2018 01:18, James McCoy wrote: > On Thu, Dec 27, 2018 at 12:18:11AM +0100, Branko Čibej wrote: >> On 26.12.2018 23:44, Daniel Shahaf wrote: >>> Branko Čibej wrote on Wed, 26 Dec 2018 23:37 +0100: >>>> On 26.12.2018 23:21, Daniel Shahaf wrote: >>>>> Branko Čibej wrote on Wed, 26 Dec 2018 22:41 +0100: >>>>>> On 26.12.2018 19:50, Daniel Shahaf wrote: >>>>>>> Haven't reviewed the rest of the patch, nor the mapping of >>>>>>> svn_error_t::apr_err values to this hierarchy. >>>>>> There is just one exception type that encapsulates all of svn_error_t, >>>>>> including the apr_err bit; that's 'svn::error'. I have no intention of >>>>>> going down the rabbit hole of having one exception type for each >>>>>> possible apr_err value! >>>>>> >>>>> Yeah, that'd be way too much; but I was thinking of two things: >>>>> >>>>> 1. apr_err can be an errno error code, not just an APR_OS_START_USERERR >>>>> code. I don't have the C++ exceptions hierarchy in mind, but I >>>>> suspect that when APR_STATUS_IS_EEXIST(err->apr_err), an svn::error >>>>> instance is not what people (and 'catch' blocks) will expect. >>>> Ah, good point. I hadn't actually thought about this side of things, as >>>> clients "shouldn't" have to worry about them iff our error messages make >>>> any sense. But, yes, adding such predicates would be a big help. >>>> >>>> They don't actually have to be part of svn::error, I'd make them >>>> namespace-scope functions, e.g.: >>>> >>>> bool svn::error_is_eexist(const svn::error& e) noexcept; >>>> >>>> >>>> the point being that the svn::error object serves as both an exception >>>> type and a detailed error description (and that's the reason for >>>> deriving svn::cancelled from svn::error). >>> I don't disagree with adding such predicates, but they aren't my point. >>> What I was trying to say is, doesn't the standard C++ exception >>> hierarchy have some std::* exception class for, say, IO errors? In >>> which case, C++ consumers might be surprised that an svn::error object >>> with apr_err==EEXIST isn't caught by their 'catch' clauses for std::* IO >>> errors? >> Not so much. Or at least not as detailed as you'd think: >> >> https://en.cppreference.com/w/cpp/error/exception > Don't forget the system error stuff introduced in c++11: > > https://en.cppreference.com/w/cpp/header/system_error
Good point, we should be able to map that. http://subversion.apache.org/issue/4799 -- Brane
