From 320d8694fec25ed148613684543b5a0504a046ae Mon Sep 17 00:00:00 2001 From: Siep Kroonenberg Date: Thu, 17 Feb 2011 17:57:31 +0000 Subject: New tlperl part XIV git-svn-id: svn://tug.org/texlive/trunk@21436 c570f23f-e606-0410-a88d-b1316a301751 --- Master/tlpkg/tlperl/lib/autodie/exception.pm | 741 +++++++++++++++++++++ .../tlpkg/tlperl/lib/autodie/exception/system.pm | 81 +++ Master/tlpkg/tlperl/lib/autodie/hints.pm | 598 +++++++++++++++++ 3 files changed, 1420 insertions(+) create mode 100644 Master/tlpkg/tlperl/lib/autodie/exception.pm create mode 100644 Master/tlpkg/tlperl/lib/autodie/exception/system.pm create mode 100644 Master/tlpkg/tlperl/lib/autodie/hints.pm (limited to 'Master/tlpkg/tlperl/lib/autodie') diff --git a/Master/tlpkg/tlperl/lib/autodie/exception.pm b/Master/tlpkg/tlperl/lib/autodie/exception.pm new file mode 100644 index 00000000000..8646099c4c8 --- /dev/null +++ b/Master/tlpkg/tlperl/lib/autodie/exception.pm @@ -0,0 +1,741 @@ +package autodie::exception; +use 5.008; +use strict; +use warnings; +use Carp qw(croak); + +our $DEBUG = 0; + +use overload + q{""} => "stringify" +; + +# Overload smart-match only if we're using 5.10 + +use if ($] >= 5.010), overload => '~~' => "matches"; + +our $VERSION = '2.06_01'; + +my $PACKAGE = __PACKAGE__; # Useful to have a scalar for hash keys. + +=head1 NAME + +autodie::exception - Exceptions from autodying functions. + +=head1 SYNOPSIS + + eval { + use autodie; + + open(my $fh, '<', 'some_file.txt'); + + ... + }; + + if (my $E = $@) { + say "Ooops! ",$E->caller," had problems: $@"; + } + + +=head1 DESCRIPTION + +When an L enabled function fails, it generates an +C object. This can be interrogated to +determine further information about the error that occurred. + +This document is broken into two sections; those methods that +are most useful to the end-developer, and those methods for +anyone wishing to subclass or get very familiar with +C. + +=head2 Common Methods + +These methods are intended to be used in the everyday dealing +of exceptions. + +The following assume that the error has been copied into +a separate scalar: + + if ($E = $@) { + ... + } + +This is not required, but is recommended in case any code +is called which may reset or alter C<$@>. + +=cut + +=head3 args + + my $array_ref = $E->args; + +Provides a reference to the arguments passed to the subroutine +that died. + +=cut + +sub args { return $_[0]->{$PACKAGE}{args}; } + +=head3 function + + my $sub = $E->function; + +The subroutine (including package) that threw the exception. + +=cut + +sub function { return $_[0]->{$PACKAGE}{function}; } + +=head3 file + + my $file = $E->file; + +The file in which the error occurred (eg, C or +C). + +=cut + +sub file { return $_[0]->{$PACKAGE}{file}; } + +=head3 package + + my $package = $E->package; + +The package from which the exceptional subroutine was called. + +=cut + +sub package { return $_[0]->{$PACKAGE}{package}; } + +=head3 caller + + my $caller = $E->caller; + +The subroutine that I the exceptional code. + +=cut + +sub caller { return $_[0]->{$PACKAGE}{caller}; } + +=head3 line + + my $line = $E->line; + +The line in C<< $E->file >> where the exceptional code was called. + +=cut + +sub line { return $_[0]->{$PACKAGE}{line}; } + +=head3 context + + my $context = $E->context; + +The context in which the subroutine was called. This can be +'list', 'scalar', or undefined (unknown). It will never be 'void', as +C always captures the return value in one way or another. + +=cut + +sub context { return $_[0]->{$PACKAGE}{context} } + +=head3 return + + my $return_value = $E->return; + +The value(s) returned by the failed subroutine. When the subroutine +was called in a list context, this will always be a reference to an +array containing the results. When the subroutine was called in +a scalar context, this will be the actual scalar returned. + +=cut + +sub return { return $_[0]->{$PACKAGE}{return} } + +=head3 errno + + my $errno = $E->errno; + +The value of C<$!> at the time when the exception occurred. + +B: This method will leave the main C class +and become part of a role in the future. You should only call +C for exceptions where C<$!> would reasonably have been +set on failure. + +=cut + +# TODO: Make errno part of a role. It doesn't make sense for +# everything. + +sub errno { return $_[0]->{$PACKAGE}{errno}; } + +=head3 eval_error + + my $old_eval_error = $E->eval_error; + +The contents of C<$@> immediately after autodie triggered an +exception. This may be useful when dealing with modules such +as L that set (but do not throw) C<$@> on error. + +=cut + +sub eval_error { return $_[0]->{$PACKAGE}{eval_error}; } + +=head3 matches + + if ( $e->matches('open') ) { ... } + + if ( $e ~~ 'open' ) { ... } + +C is used to determine whether a +given exception matches a particular role. On Perl 5.10, +using smart-match (C<~~>) with an C object +will use C underneath. + +An exception is considered to match a string if: + +=over 4 + +=item * + +For a string not starting with a colon, the string exactly matches the +package and subroutine that threw the exception. For example, +C. If the string does not contain a package name, +C is assumed. + +=item * + +For a string that does start with a colon, if the subroutine +throwing the exception I that behaviour. For example, the +C subroutine does C<:file>, C<:io> and C<:all>. + +See L for futher information. + +=back + +=cut + +{ + my (%cache); + + sub matches { + my ($this, $that) = @_; + + # TODO - Handle references + croak "UNIMPLEMENTED" if ref $that; + + my $sub = $this->function; + + if ($DEBUG) { + my $sub2 = $this->function; + warn "Smart-matching $that against $sub / $sub2\n"; + } + + # Direct subname match. + return 1 if $that eq $sub; + return 1 if $that !~ /:/ and "CORE::$that" eq $sub; + return 0 if $that !~ /^:/; + + # Cached match / check tags. + require Fatal; + + if (exists $cache{$sub}{$that}) { + return $cache{$sub}{$that}; + } + + # This rather awful looking line checks to see if our sub is in the + # list of expanded tags, caches it, and returns the result. + + return $cache{$sub}{$that} = grep { $_ eq $sub } @{ $this->_expand_tag($that) }; + } +} + +# This exists primarily so that child classes can override or +# augment it if they wish. + +sub _expand_tag { + my ($this, @args) = @_; + + return Fatal->_expand_tag(@args); +} + +=head2 Advanced methods + +The following methods, while usable from anywhere, are primarily +intended for developers wishing to subclass C, +write code that registers custom error messages, or otherwise +work closely with the C model. + +=cut + +# The table below records customer formatters. +# TODO - Should this be a package var instead? +# TODO - Should these be in a completely different file, or +# perhaps loaded on demand? Most formatters will never +# get used in most programs. + +my %formatter_of = ( + 'CORE::close' => \&_format_close, + 'CORE::open' => \&_format_open, + 'CORE::dbmopen' => \&_format_dbmopen, + 'CORE::flock' => \&_format_flock, +); + +# TODO: Our tests only check LOCK_EX | LOCK_NB is properly +# formatted. Try other combinations and ensure they work +# correctly. + +sub _format_flock { + my ($this) = @_; + + require Fcntl; + + my $filehandle = $this->args->[0]; + my $raw_mode = $this->args->[1]; + + my $mode_type; + my $lock_unlock; + + if ($raw_mode & Fcntl::LOCK_EX() ) { + $lock_unlock = "lock"; + $mode_type = "for exclusive access"; + } + elsif ($raw_mode & Fcntl::LOCK_SH() ) { + $lock_unlock = "lock"; + $mode_type = "for shared access"; + } + elsif ($raw_mode & Fcntl::LOCK_UN() ) { + $lock_unlock = "unlock"; + $mode_type = ""; + } + else { + # I've got no idea what they're trying to do. + $lock_unlock = "lock"; + $mode_type = "with mode $raw_mode"; + } + + my $cooked_filehandle; + + if ($filehandle and not ref $filehandle) { + + # A package filehandle with a name! + + $cooked_filehandle = " $filehandle"; + } + else { + # Otherwise we have a scalar filehandle. + + $cooked_filehandle = ''; + + } + + local $! = $this->errno; + + return "Can't $lock_unlock filehandle$cooked_filehandle $mode_type: $!"; + +} + +# Default formatter for CORE::dbmopen +sub _format_dbmopen { + my ($this) = @_; + my @args = @{$this->args}; + + # TODO: Presently, $args flattens out the (usually empty) hash + # which is passed as the first argument to dbmopen. This is + # a bug in our args handling code (taking a reference to it would + # be better), but for the moment we'll just examine the end of + # our arguments list for message formatting. + + my $mode = $args[-1]; + my $file = $args[-2]; + + # If we have a mask, then display it in octal, not decimal. + # We don't do this if it already looks octalish, or doesn't + # look like a number. + + if ($mode =~ /^[^\D0]\d+$/) { + $mode = sprintf("0%lo", $mode); + }; + + local $! = $this->errno; + + return "Can't dbmopen(%hash, '$file', $mode): '$!'"; +} + +# Default formatter for CORE::close + +sub _format_close { + my ($this) = @_; + my $close_arg = $this->args->[0]; + + local $! = $this->errno; + + # If we've got an old-style filehandle, mention it. + if ($close_arg and not ref $close_arg) { + return "Can't close filehandle '$close_arg': '$!'"; + } + + # TODO - This will probably produce an ugly error. Test and fix. + return "Can't close($close_arg) filehandle: '$!'"; + +} + +# Default formatter for CORE::open + +use constant _FORMAT_OPEN => "Can't open '%s' for %s: '%s'"; + +sub _format_open_with_mode { + my ($this, $mode, $file, $error) = @_; + + my $wordy_mode; + + if ($mode eq '<') { $wordy_mode = 'reading'; } + elsif ($mode eq '>') { $wordy_mode = 'writing'; } + elsif ($mode eq '>>') { $wordy_mode = 'appending'; } + + return sprintf _FORMAT_OPEN, $file, $wordy_mode, $error if $wordy_mode; + + Carp::confess("Internal autodie::exception error: Don't know how to format mode '$mode'."); + +} + +sub _format_open { + my ($this) = @_; + + my @open_args = @{$this->args}; + + # Use the default formatter for single-arg and many-arg open + if (@open_args <= 1 or @open_args >= 4) { + return $this->format_default; + } + + # For two arg open, we have to extract the mode + if (@open_args == 2) { + my ($fh, $file) = @open_args; + + if (ref($fh) eq "GLOB") { + $fh = '$fh'; + } + + my ($mode) = $file =~ m{ + ^\s* # Spaces before mode + ( + (?> # Non-backtracking subexp. + < # Reading + |>>? # Writing/appending + ) + ) + [^&] # Not an ampersand (which means a dup) + }x; + + if (not $mode) { + # Maybe it's a 2-arg open without any mode at all? + # Detect the most simple case for this, where our + # file consists only of word characters. + + if ( $file =~ m{^\s*\w+\s*$} ) { + $mode = '<' + } + else { + # Otherwise, we've got no idea what's going on. + # Use the default. + return $this->format_default; + } + } + + # Localising $! means perl make make it a pretty error for us. + local $! = $this->errno; + + return $this->_format_open_with_mode($mode, $file, $!); + } + + # Here we must be using three arg open. + + my $file = $open_args[2]; + + local $! = $this->errno; + + my $mode = $open_args[1]; + + local $@; + + my $msg = eval { $this->_format_open_with_mode($mode, $file, $!); }; + + return $msg if $msg; + + # Default message (for pipes and odd things) + + return "Can't open '$file' with mode '$open_args[1]': '$!'"; +} + +=head3 register + + autodie::exception->register( 'CORE::open' => \&mysub ); + +The C method allows for the registration of a message +handler for a given subroutine. The full subroutine name including +the package should be used. + +Registered message handlers will receive the C +object as the first parameter. + +=cut + +sub register { + my ($class, $symbol, $handler) = @_; + + croak "Incorrect call to autodie::register" if @_ != 3; + + $formatter_of{$symbol} = $handler; + +} + +=head3 add_file_and_line + + say "Problem occurred",$@->add_file_and_line; + +Returns the string C< at %s line %d>, where C<%s> is replaced with +the filename, and C<%d> is replaced with the line number. + +Primarily intended for use by format handlers. + +=cut + +# Simply produces the file and line number; intended to be added +# to the end of error messages. + +sub add_file_and_line { + my ($this) = @_; + + return sprintf(" at %s line %d\n", $this->file, $this->line); +} + +=head3 stringify + + say "The error was: ",$@->stringify; + +Formats the error as a human readable string. Usually there's no +reason to call this directly, as it is used automatically if an +C object is ever used as a string. + +Child classes can override this method to change how they're +stringified. + +=cut + +sub stringify { + my ($this) = @_; + + my $call = $this->function; + + if ($DEBUG) { + my $dying_pkg = $this->package; + my $sub = $this->function; + my $caller = $this->caller; + warn "Stringifing exception for $dying_pkg :: $sub / $caller / $call\n"; + } + + # TODO - This isn't using inheritance. Should it? + if ( my $sub = $formatter_of{$call} ) { + return $sub->($this) . $this->add_file_and_line; + } + + return $this->format_default . $this->add_file_and_line; + +} + +=head3 format_default + + my $error_string = $E->format_default; + +This produces the default error string for the given exception, +I. It is primarily +intended to be called from a message handler when they have +been passed an exception they don't want to format. + +Child classes can override this method to change how default +messages are formatted. + +=cut + +# TODO: This produces ugly errors. Is there any way we can +# dig around to find the actual variable names? I know perl 5.10 +# does some dark and terrible magicks to find them for undef warnings. + +sub format_default { + my ($this) = @_; + + my $call = $this->function; + + local $! = $this->errno; + + # TODO: This is probably a good idea for CORE, is it + # a good idea for other subs? + + # Trim package name off dying sub for error messages. + $call =~ s/.*:://; + + # Walk through all our arguments, and... + # + # * Replace undef with the word 'undef' + # * Replace globs with the string '$fh' + # * Quote all other args. + + my @args = @{ $this->args() }; + + foreach my $arg (@args) { + if (not defined($arg)) { $arg = 'undef' } + elsif (ref($arg) eq "GLOB") { $arg = '$fh' } + else { $arg = qq{'$arg'} } + } + + # Format our beautiful error. + + return "Can't $call(". join(q{, }, @args) . "): $!" ; + + # TODO - Handle user-defined errors from hash. + + # TODO - Handle default error messages. + +} + +=head3 new + + my $error = autodie::exception->new( + args => \@_, + function => "CORE::open", + errno => $!, + context => 'scalar', + return => undef, + ); + + +Creates a new C object. Normally called +directly from an autodying function. The C argument +is required, its the function we were trying to call that +generated the exception. The C parameter is optional. + +The C value is optional. In versions of C +1.99 and earlier the code would try to automatically use the +current value of C<$!>, but this was unreliable and is no longer +supported. + +Atrributes such as package, file, and caller are determined +automatically, and cannot be specified. + +=cut + +sub new { + my ($class, @args) = @_; + + my $this = {}; + + bless($this,$class); + + # I'd love to use EVERY here, but it causes our code to die + # because it wants to stringify our objects before they're + # initialised, causing everything to explode. + + $this->_init(@args); + + return $this; +} + +sub _init { + + my ($this, %args) = @_; + + # Capturing errno here is not necessarily reliable. + my $original_errno = $!; + + our $init_called = 1; + + my $class = ref $this; + + # We're going to walk up our call stack, looking for the + # first thing that doesn't look like our exception + # code, autodie/Fatal, or some whacky eval. + + my ($package, $file, $line, $sub); + + my $depth = 0; + + while (1) { + $depth++; + + ($package, $file, $line, $sub) = CORE::caller($depth); + + # Skip up the call stack until we find something outside + # of the Fatal/autodie/eval space. + + next if $package->isa('Fatal'); + next if $package->isa($class); + next if $package->isa(__PACKAGE__); + next if $file =~ /^\(eval\s\d+\)$/; + + last; + + } + + # We now have everything correct, *except* for our subroutine + # name. If it's __ANON__ or (eval), then we need to keep on + # digging deeper into our stack to find the real name. However we + # don't update our other information, since that will be correct + # for our current exception. + + my $first_guess_subroutine = $sub; + + while (defined $sub and $sub =~ /^\(eval\)$|::__ANON__$/) { + $depth++; + + $sub = (CORE::caller($depth))[3]; + } + + # If we end up falling out the bottom of our stack, then our + # __ANON__ guess is the best we can get. This includes situations + # where we were called from the top level of a program. + + if (not defined $sub) { + $sub = $first_guess_subroutine; + } + + $this->{$PACKAGE}{package} = $package; + $this->{$PACKAGE}{file} = $file; + $this->{$PACKAGE}{line} = $line; + $this->{$PACKAGE}{caller} = $sub; + $this->{$PACKAGE}{package} = $package; + + $this->{$PACKAGE}{errno} = $args{errno} || 0; + + $this->{$PACKAGE}{context} = $args{context}; + $this->{$PACKAGE}{return} = $args{return}; + $this->{$PACKAGE}{eval_error} = $args{eval_error}; + + $this->{$PACKAGE}{args} = $args{args} || []; + $this->{$PACKAGE}{function}= $args{function} or + croak("$class->new() called without function arg"); + + return $this; + +} + +1; + +__END__ + +=head1 SEE ALSO + +L, L + +=head1 LICENSE + +Copyright (C)2008 Paul Fenwick + +This is free software. You may modify and/or redistribute this +code under the same terms as Perl 5.10 itself, or, at your option, +any later version of Perl 5. + +=head1 AUTHOR + +Paul Fenwick Epjf@perltraining.com.auE diff --git a/Master/tlpkg/tlperl/lib/autodie/exception/system.pm b/Master/tlpkg/tlperl/lib/autodie/exception/system.pm new file mode 100644 index 00000000000..07cd1c9a038 --- /dev/null +++ b/Master/tlpkg/tlperl/lib/autodie/exception/system.pm @@ -0,0 +1,81 @@ +package autodie::exception::system; +use 5.008; +use strict; +use warnings; +use base 'autodie::exception'; +use Carp qw(croak); + +our $VERSION = '2.06_01'; + +my $PACKAGE = __PACKAGE__; + +=head1 NAME + +autodie::exception::system - Exceptions from autodying system(). + +=head1 SYNOPSIS + + eval { + use autodie qw(system); + + system($cmd, @args); + + }; + + if (my $E = $@) { + say "Ooops! ",$E->caller," had problems: $@"; + } + + +=head1 DESCRIPTION + +This is a L class for failures from the +C command. + +Presently there is no way to interrogate an C +object for the command, exit status, and other information you'd expect +such an object to hold. The interface will be expanded to accommodate +this in the future. + +=cut + +sub _init { + my ($this, %args) = @_; + + $this->{$PACKAGE}{message} = $args{message} + || croak "'message' arg not supplied to autodie::exception::system->new"; + + return $this->SUPER::_init(%args); + +} + +=head2 stringify + +When stringified, C objects currently +use the message generated by L. + +=cut + +sub stringify { + + my ($this) = @_; + + return $this->{$PACKAGE}{message} . $this->add_file_and_line; + +} + +1; + +__END__ + +=head1 LICENSE + +Copyright (C)2008 Paul Fenwick + +This is free software. You may modify and/or redistribute this +code under the same terms as Perl 5.10 itself, or, at your option, +any later version of Perl 5. + +=head1 AUTHOR + +Paul Fenwick Epjf@perltraining.com.auE diff --git a/Master/tlpkg/tlperl/lib/autodie/hints.pm b/Master/tlpkg/tlperl/lib/autodie/hints.pm new file mode 100644 index 00000000000..e7be03a047a --- /dev/null +++ b/Master/tlpkg/tlperl/lib/autodie/hints.pm @@ -0,0 +1,598 @@ +package autodie::hints; + +use strict; +use warnings; + +use constant PERL58 => ( $] < 5.009 ); + +our $VERSION = '2.06_01'; + +=head1 NAME + +autodie::hints - Provide hints about user subroutines to autodie + +=head1 SYNOPSIS + + package Your::Module; + + our %DOES = ( 'autodie::hints::provider' => 1 ); + + sub AUTODIE_HINTS { + return { + foo => { scalar => HINTS, list => SOME_HINTS }, + bar => { scalar => HINTS, list => MORE_HINTS }, + } + } + + # Later, in your main program... + + use Your::Module qw(foo bar); + use autodie qw(:default foo bar); + + foo(); # succeeds or dies based on scalar hints + + # Alternatively, hints can be set on subroutines we've + # imported. + + use autodie::hints; + use Some::Module qw(think_positive); + + BEGIN { + autodie::hints->set_hints_for( + \&think_positive, + { + fail => sub { $_[0] <= 0 } + } + ) + } + use autodie qw(think_positive); + + think_positive(...); # Returns positive or dies. + + +=head1 DESCRIPTION + +=head2 Introduction + +The L pragma is very smart when it comes to working with +Perl's built-in functions. The behaviour for these functions are +fixed, and C knows exactly how they try to signal failure. + +But what about user-defined subroutines from modules? If you use +C on a user-defined subroutine then it assumes the following +behaviour to demonstrate failure: + +=over + +=item * + +A false value, in scalar context + +=item * + +An empty list, in list context + +=item * + +A list containing a single undef, in list context + +=back + +All other return values (including the list of the single zero, and the +list containing a single empty string) are considered successful. However, +real-world code isn't always that easy. Perhaps the code you're working +with returns a string containing the word "FAIL" upon failure, or a +two element list containing C<(undef, "human error message")>. To make +autodie work with these sorts of subroutines, we have +the I. + +The hinting interface allows I to be provided to C +on how it should detect failure from user-defined subroutines. While +these I be provided by the end-user of C, they are ideally +written into the module itself, or into a helper module or sub-class +of C itself. + +=head2 What are hints? + +A I is a subroutine or value that is checked against the +return value of an autodying subroutine. If the match returns true, +C considers the subroutine to have failed. + +If the hint provided is a subroutine, then C will pass +the complete return value to that subroutine. If the hint is +any other value, then C will smart-match against the +value provided. In Perl 5.8.x there is no smart-match operator, and as such +only subroutine hints are supported in these versions. + +Hints can be provided for both scalar and list contexts. Note +that an autodying subroutine will never see a void context, as +C always needs to capture the return value for examination. +Autodying subroutines called in void context act as if they're called +in a scalar context, but their return value is discarded after it +has been checked. + +=head2 Example hints + +Hints may consist of scalars, array references, regular expressions and +subroutine references. You can specify different hints for how +failure should be identified in scalar and list contexts. + +These examples apply for use in the C subroutine and when +calling Cset_hints_for()>. + +The most common context-specific hints are: + + # Scalar failures always return undef: + { scalar => undef } + + # Scalar failures return any false value [default expectation]: + { scalar => sub { ! $_[0] } } + + # Scalar failures always return zero explicitly: + { scalar => '0' } + + # List failures always return an empty list: + { list => [] } + + # List failures return () or (undef) [default expectation]: + { list => sub { ! @_ || @_ == 1 && !defined $_[0] } } + + # List failures return () or a single false value: + { list => sub { ! @_ || @_ == 1 && !$_[0] } } + + # List failures return (undef, "some string") + { list => sub { @_ == 2 && !defined $_[0] } } + + # Unsuccessful foo() returns 'FAIL' or '_FAIL' in scalar context, + # returns (-1) in list context... + autodie::hints->set_hints_for( + \&foo, + { + scalar => qr/^ _? FAIL $/xms, + list => [-1], + } + ); + + # Unsuccessful foo() returns 0 in all contexts... + autodie::hints->set_hints_for( + \&foo, + { + scalar => 0, + list => [0], + } + ); + +This "in all contexts" construction is very common, and can be +abbreviated, using the 'fail' key. This sets both the C +and C hints to the same value: + + # Unsuccessful foo() returns 0 in all contexts... + autodie::hints->set_hints_for( + \&foo, + { + fail => sub { @_ == 1 and defined $_[0] and $_[0] == 0 } + } + ); + + # Unsuccessful think_positive() returns negative number on failure... + autodie::hints->set_hints_for( + \&think_positive, + { + fail => sub { $_[0] < 0 } + } + ); + + # Unsuccessful my_system() returns non-zero on failure... + autodie::hints->set_hints_for( + \&my_system, + { + fail => sub { $_[0] != 0 } + } + ); + +=head1 Manually setting hints from within your program + +If you are using a module which returns something special on failure, then +you can manually create hints for each of the desired subroutines. Once +the hints are specified, they are available for all files and modules loaded +thereafter, thus you can move this work into a module and it will still +work. + + use Some::Module qw(foo bar); + use autodie::hints; + + autodie::hints->set_hints_for( + \&foo, + { + scalar => SCALAR_HINT, + list => LIST_HINT, + } + ); + autodie::hints->set_hints_for( + \&bar, + { fail => SOME_HINT, } + ); + +It is possible to pass either a subroutine reference (recommended) or a fully +qualified subroutine name as the first argument. This means you can set hints +on modules that I get loaded: + + use autodie::hints; + autodie::hints->set_hints_for( + 'Some::Module:bar', { fail => SCALAR_HINT, } + ); + +This technique is most useful when you have a project that uses a +lot of third-party modules. You can define all your possible hints +in one-place. This can even be in a sub-class of autodie. For +example: + + package my::autodie; + + use parent qw(autodie); + use autodie::hints; + + autodie::hints->set_hints_for(...); + + 1; + +You can now C, which will work just like the standard +C, but is now aware of any hints that you've set. + +=head1 Adding hints to your module + +C provides a passive interface to allow you to declare hints for +your module. These hints will be found and used by C if it +is loaded, but otherwise have no effect (or dependencies) without autodie. +To set these, your module needs to declare that it I the +C role. This can be done by writing your +own C method, using a system such as C to handle +the heavy-lifting for you, or declaring a C<%DOES> package variable +with a C key and a corresponding true value. + +Note that checking for a C<%DOES> hash is an C-only +short-cut. Other modules do not use this mechanism for checking +roles, although you can use the C module from the +CPAN to allow it. + +In addition, you must define a C subroutine that returns +a hash-reference containing the hints for your subroutines: + + package Your::Module; + + # We can use the Class::DOES from the CPAN to declare adherence + # to a role. + + use Class::DOES 'autodie::hints::provider' => 1; + + # Alternatively, we can declare the role in %DOES. Note that + # this is an autodie specific optimisation, although Class::DOES + # can be used to promote this to a true role declaration. + + our %DOES = ( 'autodie::hints::provider' => 1 ); + + # Finally, we must define the hints themselves. + + sub AUTODIE_HINTS { + return { + foo => { scalar => HINTS, list => SOME_HINTS }, + bar => { scalar => HINTS, list => MORE_HINTS }, + baz => { fail => HINTS }, + } + } + +This allows your code to set hints without relying on C and +C being loaded, or even installed. In this way your +code can do the right thing when C is installed, but does not +need to depend upon it to function. + +=head1 Insisting on hints + +When a user-defined subroutine is wrapped by C, it will +use hints if they are available, and otherwise reverts to the +I described in the introduction of this document. +This can be problematic if we expect a hint to exist, but (for +whatever reason) it has not been loaded. + +We can ask autodie to I that a hint be used by prefixing +an exclamation mark to the start of the subroutine name. A lone +exclamation mark indicates that I subroutines after it must +have hints declared. + + # foo() and bar() must have their hints defined + use autodie qw( !foo !bar baz ); + + # Everything must have hints (recommended). + use autodie qw( ! foo bar baz ); + + # bar() and baz() must have their hints defined + use autodie qw( foo ! bar baz ); + + # Enable autodie for all of Perl's supported built-ins, + # as well as for foo(), bar() and baz(). Everything must + # have hints. + use autodie qw( ! :all foo bar baz ); + +If hints are not available for the specified subroutines, this will cause a +compile-time error. Insisting on hints for Perl's built-in functions +(eg, C and C) is always successful. + +Insisting on hints is I recommended. + +=cut + +# TODO: implement regular expression hints + +use constant UNDEF_ONLY => sub { not defined $_[0] }; +use constant EMPTY_OR_UNDEF => sub { + ! @_ or + @_==1 && !defined $_[0] +}; + +use constant EMPTY_ONLY => sub { @_ == 0 }; +use constant EMPTY_OR_FALSE => sub { + ! @_ or + @_==1 && !$_[0] +}; + +use constant SINGLE_TRUE => sub { @_ == 1 and not $_[0] }; + +use constant DEFAULT_HINTS => { + scalar => UNDEF_ONLY, + list => EMPTY_OR_UNDEF, +}; + + +use constant HINTS_PROVIDER => 'autodie::hints::provider'; + +use base qw(Exporter); + +our $DEBUG = 0; + +# Only ( undef ) is a strange but possible situation for very +# badly written code. It's not supported yet. + +my %Hints = ( + 'File::Copy::copy' => { scalar => SINGLE_TRUE, list => SINGLE_TRUE }, + 'File::Copy::move' => { scalar => SINGLE_TRUE, list => SINGLE_TRUE }, + 'File::Copy::cp' => { scalar => SINGLE_TRUE, list => SINGLE_TRUE }, + 'File::Copy::mv' => { scalar => SINGLE_TRUE, list => SINGLE_TRUE }, +); + +# Start by using Sub::Identify if it exists on this system. + +eval { require Sub::Identify; Sub::Identify->import('get_code_info'); }; + +# If it doesn't exist, we'll define our own. This code is directly +# taken from Rafael Garcia's Sub::Identify 0.04, used under the same +# license as Perl itself. + +if ($@) { + require B; + + no warnings 'once'; + + *get_code_info = sub ($) { + + my ($coderef) = @_; + ref $coderef or return; + my $cv = B::svref_2object($coderef); + $cv->isa('B::CV') or return; + # bail out if GV is undefined + $cv->GV->isa('B::SPECIAL') and return; + + return ($cv->GV->STASH->NAME, $cv->GV->NAME); + }; + +} + +sub sub_fullname { + return join( '::', get_code_info( $_[1] ) ); +} + +my %Hints_loaded = (); + +sub load_hints { + my ($class, $sub) = @_; + + my ($package) = ( $sub =~ /(.*)::/ ); + + if (not defined $package) { + require Carp; + Carp::croak( + "Internal error in autodie::hints::load_hints - no package found. + "); + } + + # Do nothing if we've already tried to load hints for + # this package. + return if $Hints_loaded{$package}++; + + my $hints_available = 0; + + { + no strict 'refs'; ## no critic + + if ($package->can('DOES') and $package->DOES(HINTS_PROVIDER) ) { + $hints_available = 1; + } + elsif ( PERL58 and $package->isa(HINTS_PROVIDER) ) { + $hints_available = 1; + } + elsif ( ${"${package}::DOES"}{HINTS_PROVIDER.""} ) { + $hints_available = 1; + } + } + + return if not $hints_available; + + my %package_hints = %{ $package->AUTODIE_HINTS }; + + foreach my $sub (keys %package_hints) { + + my $hint = $package_hints{$sub}; + + # Ensure we have a package name. + $sub = "${package}::$sub" if $sub !~ /::/; + + # TODO - Currently we don't check for conflicts, should we? + $Hints{$sub} = $hint; + + $class->normalise_hints(\%Hints, $sub); + } + + return; + +} + +sub normalise_hints { + my ($class, $hints, $sub) = @_; + + if ( exists $hints->{$sub}->{fail} ) { + + if ( exists $hints->{$sub}->{scalar} or + exists $hints->{$sub}->{list} + ) { + # TODO: Turn into a proper diagnostic. + require Carp; + local $Carp::CarpLevel = 1; + Carp::croak("fail hints cannot be provided with either scalar or list hints for $sub"); + } + + # Set our scalar and list hints. + + $hints->{$sub}->{scalar} = + $hints->{$sub}->{list} = delete $hints->{$sub}->{fail}; + + return; + + } + + # Check to make sure all our hints exist. + + foreach my $hint (qw(scalar list)) { + if ( not exists $hints->{$sub}->{$hint} ) { + # TODO: Turn into a proper diagnostic. + require Carp; + local $Carp::CarpLevel = 1; + Carp::croak("$hint hint missing for $sub"); + } + } + + return; +} + +sub get_hints_for { + my ($class, $sub) = @_; + + my $subname = $class->sub_fullname( $sub ); + + # If we have hints loaded for a sub, then return them. + + if ( exists $Hints{ $subname } ) { + return $Hints{ $subname }; + } + + # If not, we try to load them... + + $class->load_hints( $subname ); + + # ...and try again! + + if ( exists $Hints{ $subname } ) { + return $Hints{ $subname }; + } + + # It's the caller's responsibility to use defaults if desired. + # This allows on autodie to insist on hints if needed. + + return; + +} + +sub set_hints_for { + my ($class, $sub, $hints) = @_; + + if (ref $sub) { + $sub = $class->sub_fullname( $sub ); + + require Carp; + + $sub or Carp::croak("Attempts to set_hints_for unidentifiable subroutine"); + } + + if ($DEBUG) { + warn "autodie::hints: Setting $sub to hints: $hints\n"; + } + + $Hints{ $sub } = $hints; + + $class->normalise_hints(\%Hints, $sub); + + return; +} + +1; + +__END__ + + +=head1 Diagnostics + +=over 4 + +=item Attempts to set_hints_for unidentifiable subroutine + +You've called C<< autodie::hints->set_hints_for() >> using a subroutine +reference, but that reference could not be resolved back to a +subroutine name. It may be an anonymous subroutine (which can't +be made autodying), or may lack a name for other reasons. + +If you receive this error with a subroutine that has a real name, +then you may have found a bug in autodie. See L +for how to report this. + +=item fail hints cannot be provided with either scalar or list hints for %s + +When defining hints, you can either supply both C and +C keywords, I you can provide a single C keyword. +You can't mix and match them. + +=item %s hint missing for %s + +You've provided either a C hint without supplying +a C hint, or vice-versa. You I supply both C +and C hints, I a single C hint. + +=back + +=head1 ACKNOWLEDGEMENTS + +=over + +=item * + +Dr Damian Conway for suggesting the hinting interface and providing the +example usage. + +=item * + +Jacinta Richardson for translating much of my ideas into this +documentation. + +=back + +=head1 AUTHOR + +Copyright 2009, Paul Fenwick Epjf@perltraining.com.auE + +=head1 LICENSE + +This module is free software. You may distribute it under the +same terms as Perl itself. + +=head1 SEE ALSO + +L, L + +=cut -- cgit v1.2.3