use Carp;
use overload ();
-use Memoize;
use Scalar::Util qw(reftype);
use Try::Tiny;
=head1 SYNOPSIS
+ use Eval::Closure;
+
+ my $code = eval_closure(
+ source => 'sub { $foo++ }',
+ environment => {
+ '$foo' => \1,
+ },
+ );
+
+ warn $code->(); # 1
+ warn $code->(); # 2
+
+ my $code2 = eval_closure(
+ source => 'sub { $code->() }',
+ ); # dies, $code isn't in scope
+
=head1 DESCRIPTION
+String eval is often used for dynamic code generation. For instance, C<Moose>
+uses it heavily, to generate inlined versions of accessors and constructors,
+which speeds code up at runtime by a significant amount. String eval is not
+without its issues however - it's difficult to control the scope it's used in
+(which determines which variables are in scope inside the eval), and it's easy
+to miss compilation errors, since eval catches them and sticks them in $@
+instead.
+
+This module attempts to solve these problems. It provides an C<eval_closure>
+function, which evals a string in a clean environment, other than a fixed list
+of specified variables. Compilation errors are rethrown automatically.
+
=cut
=func eval_closure(%args)
+This function provides the main functionality of this module. It is exported by
+default. It takes a hash of parameters, with these keys being valid:
+
+=over 4
+
+=item source
+
+The string to be evaled. It should end by returning a code reference. It can
+access any variable declared in the C<environment> parameter (and only those
+variables). It can be either a string, or an arrayref of lines (which will be
+joined with newlines to produce the string).
+
+=item environment
+
+The environment to provide to the eval. This should be a hashref, mapping
+variable names (including sigils) to references of the appropriate type. For
+instance, a valid value for environment would be C<< { '@foo' => [] } >> (which
+would allow the generated function to use an array named C<@foo>). Generally,
+this is used to allow the generated function to access externally defined
+variables (so you would pass in a reference to a variable that already exists).
+
+=item description
+
+This lets you provide a bit more information in backtraces. Normally, when a
+function that was generated through string eval is called, that stack frame
+will show up as "(eval n)", where 'n' is a sequential identifier for every
+string eval that has happened so far in the program. Passing a C<description>
+parameter lets you override that to something more useful (for instance,
+L<Moose> overrides the description for accessors to something like "accessor
+foo at MyClass.pm, line 123").
+
+=item line
+
+This lets you override the particular line number that appears in backtraces,
+much like the C<description> option. The default is 1.
+
+=item terse_error
+
+Normally, this function appends the source code that failed to compile, and
+prepends some explanatory text. Setting this option to true suppresses that
+behavior so you get only the compilation error that Perl actually reported.
+
+=back
+
=cut
sub eval_closure {
$args{source} = _canonicalize_source($args{source});
_validate_env($args{environment} ||= {});
- $args{source} = _line_directive($args{description}) . $args{source}
- if defined $args{description};
+ $args{source} = _line_directive(@args{qw(line description)})
+ . $args{source}
+ if defined $args{description} && !($^P & 0x10);
my ($code, $e) = _clean_eval_closure(@args{qw(source environment)});
- croak("Failed to compile source: $e\n\nsource:\n$args{source}")
- unless $code;
+ if (!$code) {
+ if ($args{terse_error}) {
+ die "$e\n";
+ }
+ else {
+ croak("Failed to compile source: $e\n\nsource:\n$args{source}")
+ }
+ }
return $code;
}
}
sub _line_directive {
- my ($description) = @_;
+ my ($line, $description) = @_;
+
+ $line = 1 unless defined($line);
- return qq{#line 1 "$description"\n};
+ return qq{#line $line "$description"\n};
}
sub _clean_eval_closure {
- my ($source, $captures) = @_;
+ my ($source, $captures) = @_;
+
+ my @capture_keys = sort keys %$captures;
if ($ENV{EVAL_CLOSURE_PRINT_SOURCE}) {
- _dump_source(_make_compiler_source(@_));
+ _dump_source(_make_compiler_source($source, @capture_keys));
}
- my @capture_keys = sort keys %$captures;
my ($compiler, $e) = _make_compiler($source, @capture_keys);
my $code;
if (defined $compiler) {
}
sub _make_compiler {
- local $@;
- local $SIG{__DIE__};
- my $compiler = eval _make_compiler_source(@_);
- my $e = $@;
- return ($compiler, $e);
+ my $source = _make_compiler_source(@_);
+
+ return @{ _clean_eval($source) };
+}
+
+$Eval::Closure::SANDBOX_ID = 0;
+
+sub _clean_eval {
+ $Eval::Closure::SANDBOX_ID++;
+ return eval <<EVAL;
+package Eval::Closure::Sandbox_$Eval::Closure::SANDBOX_ID;
+local \$@;
+local \$SIG{__DIE__};
+my \$compiler = eval \$_[0];
+my \$e = \$@;
+[ \$compiler, \$e ];
+EVAL
}
-memoize('_make_compiler');
sub _make_compiler_source {
my ($source, @capture_keys) = @_;
Perl::Tidy::perltidy(
source => \$source,
destination => \$output,
+ argv => [],
);
}
else {
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