Re: write(f)ln style exception factory
15-Jun-2014 02:03, Element 126 пишет: On 06/14/2014 09:04 PM, Dmitry Olshansky wrote: Recalling the previous discussion of throwing exception being costly, I thought the idiom of pay as you go is worth incorporating into the standard library. In brief: throw exception(CPU temperature is below, 2.5, K); vs throw new Exception(text(CPU temperature is below, 2.5, K)); or: enforce(false, text(CPU temperature is below, 2.5, K)); The benefit that the latter will only construct string if printing is indeed requested. Proof of concept: https://gist.github.com/DmitryOlshansky/59ec5953874bc1985ac5 The problem with it is that for some reason writeln of exception won't compile while thrown exception is printed just fine by the trace handler. Thoughts? --- writeln(myException.info); --- Is it what you are looking for ? No, normal exceptions print just fine. e.g. writeln(new Exception(abc)); I'm wondering what's wrong the one I defined, the error message seems to indicate that it doesn't have toString. It's wrong as there is one derived from Exception. Workaround was to use alias toString = Base.toString; -- Dmitry Olshansky
Re: write(f)ln style exception factory
On 2014-06-15 11:40, Dmitry Olshansky wrote: No, normal exceptions print just fine. e.g. writeln(new Exception(abc)); I'm wondering what's wrong the one I defined, the error message seems to indicate that it doesn't have toString. It's wrong as there is one derived from Exception. Workaround was to use alias toString = Base.toString; Is this because writeln tries to use the one without parameters? If you override one method, which as overloads, you need to override all overloads or bring them into the same overload set with an alias, as you've done above. A base class and subclass have different overload sets [1]. [1] http://dlang.org/hijack.html search for Derived Class Member Function Hijacking. -- /Jacob Carlborg
Re: write(f)ln style exception factory
On 06/14/2014 09:04 PM, Dmitry Olshansky wrote: Recalling the previous discussion of throwing exception being costly, I thought the idiom of pay as you go is worth incorporating into the standard library. In brief: throw exception(CPU temperature is below, 2.5, K); vs throw new Exception(text(CPU temperature is below, 2.5, K)); or: enforce(false, text(CPU temperature is below, 2.5, K)); The benefit that the latter will only construct string if printing is indeed requested. Proof of concept: https://gist.github.com/DmitryOlshansky/59ec5953874bc1985ac5 The problem with it is that for some reason writeln of exception won't compile while thrown exception is printed just fine by the trace handler. Thoughts? --- writeln(myException.info); --- Is it what you are looking for ?
