On 6 October 2010 23:01, Jakub Narebski <jnareb@xxxxxxxxx> wrote:
> +# creates get_depth() and set_depth($depth) etc. methods
> +foreach my $i (qw(depth root namespace)) {
> + Â Â Â my $field = $i;
> + Â Â Â no strict 'refs';
For each item, you'll set "no strict refs"? This might be better off
outside the loop. It's still scoped appropriately inside the
subroutine.
> + Â Â Â my $file = $self->path_to_key($key);
> + Â Â Â return undef unless (defined $file && -f $file);
PBP (Perl Best Practises) will tell you that explicitly returning
undef is discouraged -- "undef" should be reserved for those errors
you cannot handle, not ones you don't want to.
> +
> + Â Â Â # Fast slurp, adapted from File::Slurp::read, with unnecessary options removed
> + Â Â Â # via CHI::Driver::File (from CHI-0.33)
> + Â Â Â my $buf = '';
> + Â Â Â open my $read_fh, '<', $file
> + Â Â Â Â Â Â Â or return undef;
Ditto.
> + Â Â Â binmode $read_fh, ':raw';
> +
> + Â Â Â my $size_left = -s $read_fh;
> +
> + Â Â Â while ($size_left > 0) {
> + Â Â Â Â Â Â Â my $read_cnt = sysread($read_fh, $buf, $size_left, length($buf));
> + Â Â Â Â Â Â Â return undef unless defined $read_cnt;
Ditto.
> + Â Â Â Â Â Â Â last if $read_cnt == 0;
> + Â Â Â Â Â Â Â $size_left -= $read_cnt;
> + Â Â Â Â Â Â Â #last if $size_left <= 0;
> + Â Â Â }
> +
> + Â Â Â close $read_fh
> + Â Â Â Â Â Â Â or die "Couldn't close file '$file' opened for reading: $!";
> + Â Â Â return $buf;
> +}
"use Carp;" would be more useful here, and hence croak() and confess().
> +sub store {
> + Â Â Â my ($self, $key, $data) = @_;
> +
> + Â Â Â my $dir;
> + Â Â Â my $file = $self->path_to_key($key, \$dir);
> + Â Â Â return undef unless (defined $file && defined $dir);
See above.
> + Â Â Â # ensure that directory leading to cache file exists
> + Â Â Â if (!-d $dir) {
> + Â Â Â Â Â Â Â eval { mkpath($dir, 0, 0777); 1 }
> + Â Â Â Â Â Â Â Â Â Â Â or die "Couldn't create leading directory '$dir' (mkpath): $!";
> + Â Â Â }
Why is this eval()ed? It will still return false and set $! appropriately.
> + Â Â Â # generate a temporary file
> + Â Â Â my ($temp_fh, $tempname) = $self->_tempfile_to_path($file, $dir);
> + Â Â Â chmod 0666, $tempname
> + Â Â Â Â Â Â Â or warn "Couldn't change permissions to 0666 / -rw-rw-rw- for '$tempname': $!";
> +
> + Â Â Â # Fast spew, adapted from File::Slurp::write, with unnecessary options removed
> + Â Â Â # via CHI::Driver::File (from CHI-0.33)
> + Â Â Â my $write_fh = $temp_fh;
> + Â Â Â binmode $write_fh, ':raw';
> +
> + Â Â Â my $size_left = length($data);
> + Â Â Â my $offset = 0;
> +
> + Â Â Â while ($size_left > 0) {
> + Â Â Â Â Â Â Â my $write_cnt = syswrite($write_fh, $data, $size_left, $offset);
> + Â Â Â Â Â Â Â return undef unless defined $write_cnt;
Again, with the undef.
> + Â Â Â Â Â Â Â $size_left -= $write_cnt;
> + Â Â Â Â Â Â Â $offset += $write_cnt; # == length($data);
> + Â Â Â }
> +
> + Â Â Â close $temp_fh
> + Â Â Â Â Â Â Â or die "Couldn't close temporary file '$tempname' opened for writing: $!";
> + Â Â Â rename($tempname, $file)
> + Â Â Â Â Â Â Â or die "Couldn't rename temporary file '$tempname' to '$file': $!";
> +}
> +
> +# get size of an element associated with the $key (not the size of whole cache)
> +sub get_size {
> + Â Â Â my ($self, $key) = @_;
> +
> + Â Â Â my $path = $self->path_to_key($key)
> + Â Â Â Â Â Â Â or return undef;
Again with the undef
> + Â Â Â if (-f $path) {
> + Â Â Â Â Â Â Â return -s $path;
> + Â Â Â }
> + Â Â Â return 0;
> +}
> +
> +# ......................................................................
> +# interface methods
> +
> +# Removing and expiring
> +
> +# $cache->remove($key)
> +#
> +# Remove the data associated with the $key from the cache.
> +sub remove {
> + Â Â Â my ($self, $key) = @_;
> +
> + Â Â Â my $file = $self->path_to_key($key)
> + Â Â Â Â Â Â Â or return undef;
> + Â Â Â return undef unless -f $file;
Again with the undef.
> + Â Â Â unlink($file)
> + Â Â Â Â Â Â Â or die "Couldn't remove file '$file': $!";
> +}
> +
> +# Getting and setting
> +
> +# $cache->set($key, $data);
> +#
> +# Associates $data with $key in the cache, overwriting any existing entry.
> +# Returns $data.
> +sub set {
> + Â Â Â my ($self, $key, $data) = @_;
> +
> + Â Â Â return unless (defined $key && defined $data);
return what?
> + Â Â Â $self->store($key, $data);
> +
> + Â Â Â return $data;
> +}
> +
> +# $data = $cache->get($key);
> +#
> +# Returns the data associated with $key. ÂIf $key does not exist
> +# or has expired, returns undef.
> +sub get {
> + Â Â Â my ($self, $key) = @_;
> +
> + Â Â Â my $data = $self->fetch($key)
> + Â Â Â Â Â Â Â or return undef;
> +
> + Â Â Â return $data;
> +}
> +
> +# $data = $cache->compute($key, $code);
> +#
> +# Combines the get and set operations in a single call. ÂAttempts to
> +# get $key; if successful, returns the value. ÂOtherwise, calls $code
> +# and uses the return value as the new value for $key, which is then
> +# returned.
> +sub compute {
> + Â Â Â my ($self, $key, $code) = @_;
> +
> + Â Â Â my $data = $self->get($key);
> + Â Â Â if (!defined $data) {
> + Â Â Â Â Â Â Â $data = $code->($self, $key);
> + Â Â Â Â Â Â Â $self->set($key, $data);
> + Â Â Â }
Can you guarantee $code here?
unless( defined $code and ref $code eq 'CODE' )
{
....
}
Wouldn't it be easier to eval{} this and checj $@?
[...]
-- Thomas Adam
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