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Postings from June 2008
G'day p5p,
I'm playing with a few design ideas for autodie, and would love your feedback.
== Meaning of vanilla 'use autodie' ===
Presently it's possible to:
use autodie qw(:all);
and enable autodie (lexical fatal) for all the built-ins on which autodie
could normally be used.
I'd like to float the idea that it should be possible to write:
use autodie;
and have that mean the same as 'use autodie qw(:all)'.
== system() ==
The system() built-in can't normally be overridden cleanly, because it
doesn't have a prototype. The reason there's no prototype is because the
exotic form:
system { $name } @args
doesn't take kindly to prototyping. However I'm going to suggest that we
ignore the fact that system can't be prototyped, and make it usable with
Fatal/autodie anyway. I've already written a proof-of-concept, and the side
effects are:
* Code outside the current package isn't harmed.
* Code inside the current package will generate a syntax error
if the exotic form of system is used.
* The exotic system can still be used if CORE::system { $x } @args
is used instead.
* We can have system automatically throw a nicely formatted
exception if there's a problem.
Any objections? Should system() be included when asking for 'use autodie
qw(:all)', since it means the bare exotic system() is now a syntax error?
As for the definition of "system having a problem", I'm strongly inclined to
use the same rules as IPC::System::Simple[1], namely:
* Failing to start entirely (eg, command not found)
* Returning a non-zero exit value
* Being killed by a signal
* Being passed tainted data (in taint mode)
== Dependencies ==
I'd love for autodie/Fatal.pm to be a candidate for the core (albeit
probably dual-lifed), because I feel it has such widespread potential.
While I'm very fond of low-dependency tools, I'd love to have the
opportunity to leverage Exception::Class (which in turn requires
Devel::StackTrack and Class::Data::Inheritable), and IPC::System::Simple
(which depends only on core modules) for exceptions and system() processing
respectively.
Obviously we don't want a huge influx of modules into the core, so I'd
appreciate advice here. autodie can exist without these modules, but it
will be reinventing the wheel, and potentially in a way that's not as good.
Thanks in advance for the feedback,
Paul
[1] http://search.cpan.org/perldoc?IPC::System::Simple
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