On 09/05/2011 09:03 PM, Carl Mäsak wrote:
> 1parrota (>):
>> 1. Should there be a way to make "die" behave like the Perl 5 version,
>> reporting the place of death unless the message is terminated by \n ?
>> The \n no longer suppresses the location indormation. I can't find a
>> definition either way in the Synopses.
> Yes, there should.
> The problem is one of the perfect being the enemy of the good. People
> pretty much agree that the mechanism shouldn't be governed by "\n" at
> the end of the error string, but no-one has suggested anything
> significantly more attractive either. So here we are, currently
> without a way to get "die" (and "warn") without location information.

FWIW the current factoring allows the catcher of the exception to
control whether a backtrace is printed. A solution is thus to catch
exceptions on the outermost level of your program, and print the
exception (but not the backtrace) there.

A cheap (but probably wrong) approach would simply be a named argument
to &die, like

die 'OH NOEZ', :suppress-backtrace

But as Larry usually points out, such a modified behavior is often a
sign of design smell.

And I guess that's what happens here: we conflate two concepts here:
Error messages that usually stem from errors that the programmer made,
and error messages for things that the user did wrong (and which I guess
is the reason one wants to surpress backtraces -- are there others?)

So I guess the exception object could contain a hint whether the error
is a user error or a programming error. All those errors that are thrown
by the Perl 6 compiler count as programming error, but we can still
provide a X::UserError class, which disables printing of backtraces by

The question is if we provide a separate sub for such cases (error() or
report-error() or so), or if we rely on something like

UserError.new(message => 'You did something wrong here').throw

or something similar.


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