On 04/23/2013 03:24 PM, Marvin Löbel wrote:
Ever since fail and assert got turned into macros, failing with a
string message has become quite line-noisy:
fail!(~"cause")
Personally I think 3 is the easiest to implement option, and nice even
without the fmt! optimisation. I already locally implemented the
necessary changes that would allow switching to it after an snapshot,
but I wanted to ask what others think.
From what you've presented, I like 3.
I agree with this sentiment in general, and agree that all these related
string-taking macros, assert, fail, debug, etc. should behave similarly,
generally accepting whatever you throw at them. It would be very
desirable I think to not duplicate the string in the case where ~str is
the only argument. This could probably be done with a trait that
converts to ~str by value (so ~str.to_str_by_val() is a no-op).
We have always had this lingering notion that fail *could* accept a
dynamically typed twiddle, called `~Any`. If we go this direction of
passing everything through `fmt!` then that becomes more complicated.
I think there will be solutions though. In the case where `fail` is
passed just one argument it could be interpreted as an instance of some
trait, Exceptiony, that can be called to cast the value to `~Any`. When
multiple arguments are passed it delegates to fmt.
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