Replacing perl-5.8.x's filehandle "layers" in perl-5.6.x

shlomif has asked for the wisdom of the Perl Monks concerning the following question:

In perl-5.8.x the binmode built-in (and "open") have added more Unicode-related layers like ":utf8" or ":encoding(iso-8859-1)". However, they are completly unavailable and throw an exception in perl-5.6.x. I'm looking for a way to replace or emulate their behaviour in perl-5.6.x.

Specifically, in XML-RSS-1.30, we have the following code:

sub save {
    my ($self, $file) = @_;
    open(OUT, ">:encoding($self->{encoding})", "$file")
      or croak "Cannot open file $file for write: $!";
    print OUT $self->as_string;
    close OUT;
}
[download]

Assuming we want the contents of $self->as_string() to be stored in the file using the encoding $self->{encoding}, what should we do in perl-5.6.x instead? Will Encode.pm be of any help?

We'll probably keep the code for perl-5.8.x as is, but also add some workarounds for perl-5.6.x.

Comment on Replacing perl-5.8.x's filehandle "layers" in perl-5.6.x Download Code

Replies are listed 'Best First'.
Re: Replacing perl-5.8.x's filehandle "layers" in perl-5.6.x by ikegami (Patriarch) on Jun 25, 2007 at 14:38 UTC
When writing, `:encoding` only makes sense if you try to print "strings of chars". Perl 5.6 doesn't have string of chars, so there can be no parallel to `:encoding`. To replace `:encoding`, you'd have to replace three things: The function that converts the string of encoded bytes to a string of chars, such as `:encoding()` on read and `decode`. Any string function used, such as regexps, `substr`, `eq`, etc. The function that converts the string of chars to a string of encoded bytes, such as `:encoding()` on write and `encode`. Basically, you need a "string of chars" class for Perl 5.6 to fill in for the native one in Perl 5.8. I don't know if such a thing exists. You really should upgrade to Perl 5.8 if you're going to deal with characters sets. (And no, Encode won't help since it allows you to do explicitly what `:encoding` does implicitly. You can't convert "string of chars" if in a version of Perl where they don't exist.)	[reply] [d/l] [select]
Re^2: Replacing perl-5.8.x's filehandle "layers" in perl-5.6.x by shlomif (Beadle) on Jun 25, 2007 at 17:11 UTC
I see. I guess we'll just default to `">", $file` and don't worry about encodings at all for Perl 5.6.x and below. I'll need to consult the other maintainer about it, though.	[reply]