07-23-2008
I can't repro that. Do you have a global variable %results or a subroutine results elsewhere in your script? (Still can't repro with either of those, but I can't come up with anything better ...) Or just a missing closing brace somewhere -- those can trigger quite misleading error messages.
What's the point of an open("long pipeline |") loop if all you want is a single value? I'd use backticks for that. Also the return on error without a proper error message looks user-hostile and fragile. (Of course if the error checking is deferred to the caller then I suppose it's as it should be.)
Last edited by era; 07-23-2008 at 02:15 AM..
Reason: Suggest use backticks
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LEARN ABOUT CENTOS
fields
fields(3pm) Perl Programmers Reference Guide fields(3pm)
NAME
fields - compile-time class fields
SYNOPSIS
{
package Foo;
use fields qw(foo bar _Foo_private);
sub new {
my Foo $self = shift;
unless (ref $self) {
$self = fields::new($self);
$self->{_Foo_private} = "this is Foo's secret";
}
$self->{foo} = 10;
$self->{bar} = 20;
return $self;
}
}
my $var = Foo->new;
$var->{foo} = 42;
# this will generate an error
$var->{zap} = 42;
# subclassing
{
package Bar;
use base 'Foo';
use fields qw(baz _Bar_private); # not shared with Foo
sub new {
my $class = shift;
my $self = fields::new($class);
$self->SUPER::new(); # init base fields
$self->{baz} = 10; # init own fields
$self->{_Bar_private} = "this is Bar's secret";
return $self;
}
}
DESCRIPTION
The "fields" pragma enables compile-time verified class fields.
NOTE: The current implementation keeps the declared fields in the %FIELDS hash of the calling package, but this may change in future
versions. Do not update the %FIELDS hash directly, because it must be created at compile-time for it to be fully useful, as is done by
this pragma.
Only valid for perl before 5.9.0:
If a typed lexical variable holding a reference is used to access a hash element and a package with the same name as the type has declared
class fields using this pragma, then the operation is turned into an array access at compile time.
The related "base" pragma will combine fields from base classes and any fields declared using the "fields" pragma. This enables field
inheritance to work properly.
Field names that start with an underscore character are made private to the class and are not visible to subclasses. Inherited fields can
be overridden but will generate a warning if used together with the "-w" switch.
Only valid for perls before 5.9.0:
The effect of all this is that you can have objects with named fields which are as compact and as fast arrays to access. This only works as
long as the objects are accessed through properly typed variables. If the objects are not typed, access is only checked at run time.
The following functions are supported:
new perl before 5.9.0: fields::new() creates and blesses a pseudo-hash comprised of the fields declared using the "fields" pragma into
the specified class.
perl 5.9.0 and higher: fields::new() creates and blesses a restricted-hash comprised of the fields declared using the "fields" pragma
into the specified class.
This function is usable with or without pseudo-hashes. It is the recommended way to construct a fields-based object.
This makes it possible to write a constructor like this:
package Critter::Sounds;
use fields qw(cat dog bird);
sub new {
my $self = shift;
$self = fields::new($self) unless ref $self;
$self->{cat} = 'meow'; # scalar element
@$self{'dog','bird'} = ('bark','tweet'); # slice
return $self;
}
phash
before perl 5.9.0:
fields::phash() can be used to create and initialize a plain (unblessed) pseudo-hash. This function should always be used instead of
creating pseudo-hashes directly.
If the first argument is a reference to an array, the pseudo-hash will be created with keys from that array. If a second argument is
supplied, it must also be a reference to an array whose elements will be used as the values. If the second array contains less
elements than the first, the trailing elements of the pseudo-hash will not be initialized. This makes it particularly useful for
creating a pseudo-hash from subroutine arguments:
sub dogtag {
my $tag = fields::phash([qw(name rank ser_num)], [@_]);
}
fields::phash() also accepts a list of key-value pairs that will be used to construct the pseudo hash. Examples:
my $tag = fields::phash(name => "Joe",
rank => "captain",
ser_num => 42);
my $pseudohash = fields::phash(%args);
perl 5.9.0 and higher:
Pseudo-hashes have been removed from Perl as of 5.10. Consider using restricted hashes or fields::new() instead. Using
fields::phash() will cause an error.
SEE ALSO
base
perl v5.16.3 2013-03-04 fields(3pm)