language selection via libxml

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

What I want to do is make my GUI startable in different languages. I would input a parameter when starting the gui (e.g. perl gui.pl english) and when initialising the widgets it would get the text from a xml file that looks like this:

<?xml version="1.0"?>
<language>
    <english>
        <widget ID="1">input</widget>
        <widget ID="2">output</widget>

    </english>
    <deutsch>
        <widget ID="1">eingabe</widget>
        <widget ID="2">ausgabe</widget>
    </deutsch>
</language>
[download]

in the text setting of widgets i call a function with the widget id as a parameter.

    sub change_lang
    {
    my $id= shift;
    my $file='lang.xml';
        my $result;
    my $parser = XML::LibXML->new();
    my $tree = $parser->parse_file($file);

    $result=$tree->findnodes("/language/$language/widget[@ID="$id"]");
    return $result;
    }
[download]

but that doesnt work ("global symbol @ID requires explicit package name"). I don't know how to get to the content of the xml with scalars in the findnodes path. how would i do this? If anyone has better ideas for implementing language change, I'd be open for it, too. I'm too much of a perl scrub.

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Re: language selection via libxml by McA (Priest) on Jan 20, 2014 at 09:40 UTC
Hi, `$result=$tree->findnodes("/language/$language/widget[@ID="$id"]");` [download] The `@ID` is interpreted by Perl as an array access. You have to escape the '@'. Best regards McA	[reply] [d/l] [select]
Re^2: language selection via libxml by tangent (Parson) on Jan 20, 2014 at 12:18 UTC
Also need to lose the quotes around $id `"/language/$language/widget[\@ID=$id]"` [download] Update: Thanks to choroba's explanations and examples below, this only works by accident, i.e. only if $id is a number. Here are some different ways of doing it: `"/language/$language/widget[\@ID='$id']" "/language/$language/widget[attribute::ID='$id']" qq\|/language/$language/widget[\@ID="$id"]\| qq\|/language/$language/widget[\@ID='$id']\| qq\|/language/$language/widget[attribute::ID="$id"]\| qq\|/language/$language/widget[attribute::ID='$id']\|` [download]	[reply] [d/l] [select]
Re^3: language selection via libxml by choroba (Cardinal) on Jan 20, 2014 at 12:29 UTC
Not really. String literals must be enclosed in quotes in XPath expressions, and XPath does not know Perl variables (unless you use XML::XSH2). لսႽ† ᥲᥒ⚪⟊Ⴙᘓᖇ Ꮅᘓᖇ⎱ Ⴙᥲ𝇋ƙᘓᖇ	[reply]
Re^4: language selection via libxml by tangent (Parson) on Jan 20, 2014 at 12:41 UTC
Re^5: language selection via libxml by choroba (Cardinal) on Jan 20, 2014 at 13:09 UTC
Some notes below your chosen depth have not been shown here
Re^5: language selection via libxml by hdb (Monsignor) on Jan 20, 2014 at 12:52 UTC
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Re: language selection via libxml (perlquote) by Anonymous Monk on Jan 20, 2014 at 09:53 UTC
If you add `use diagnostics;` it will print a more verbose error message explaining this scenario (there is no variabele @ID which you keyboarded into your string) string quoting/interpolation are explained in perlintro and Strings in Perl: quoted, interpolated and escaped You can simplify your xpaths, like this (untested , may contain typos) `sub enumerate_languages { my( $xmltree ) = @_; my @nodes = $xmltree->findnodes( '/language' ); my @langs = map { $_->tagName } @nodes; return @langs; } sub get_language { my( $xmltree, $lang ) = @_; my @nodes = $xmltree->findnodes( "/language/$lang/*" ); my %pairs ; for my $node ( @nodes ){ $pairs{ $node->getAttribute('ID') } = $node->textContent; } return %pairs; }` [download] FWIW, traditionally this is done using .po/.mo files, each language gets its own file ... gettext.. and all that ... :)	[reply] [d/l]
Re: language selection via libxml by Jenda (Abbot) on Jan 20, 2014 at 17:05 UTC
Are you sure you want to parse and reparse the XML many times for each individual widget? I'd rather parse it just once at the beginning or at most once when the language is changed. `use XML::Rules; my $parser = XML::Rules->new(rules=>{ widget => 'content by ID', language => 'pass no content', _default => 'no content' }); my $data = $parser->parse(\DATA); use Data::Dumper; print Dumper($data); # $data{english}{1} == "input" __DATA__ <?xml version="1.0"?> <language> <english> <widget ID="1">input</widget> <widget ID="2">output</widget> </english> <deutsch> <widget ID="1">eingabe</widget> <widget ID="2">ausgabe</widget> </deutsch> </language>` [download] Jenda Enoch was right!* Enjoy the last years of Rome.	[reply] [d/l]