On 12/2/23 23:12, Andrzej Krzemienski via Boost wrote:
Hi All, Two observations from reading the docs.
Why do I need a condition in scope_exit when I have a scope_fail?
There is a discussion about this in this section: https://lastique.github.io/scope/libs/scope/doc/html/scope/scope_guards.html... In short, scope_fail implies processing a failure event (for whatever definition of "failure") and scope_exit has no such connotation and can be used with arbitrary conditions. The different scope guards have different default conditions, too. Internally, both scope_success and scope_fail are implemented on top of scope_exit and leverage its support for custom condition functions.
I recommend putting warning somewhere in the docs that while using scope guards you may inadvertently read an object after move:
std::string checked(std::string name) { scope::scope_exit g{[&]{ std::clog << "checked " << name <<std::endl; }};
validate(name); return name; // name becomes moved-from }
Interesting observation, thanks.