Palm::StdAppInfo - Handles standard AppInfo block (categories)

Usually:

    package MyPDBHandler;
    use Palm::StdAppInfo();             # Note the parentheses

    @ISA = qw( Palm::StdAppInfo );

    use constant APPINFO_PADDING = 1;

    sub ParseAppInfoBlock {
        my $self = shift;
        my $data = shift;
        my $appinfo = {};

        &Palm::StdAppInfo::parse_StdAppInfo($appinfo, $data);

        $app_specific_data = $appinfo->{other};
    }

    sub PackAppInfoBlock {
        my $self = shift;
        my $retval;

        $self->{appinfo}{other} = <pack application-specific data>;
        $retval = &Palm::StdAppInfo::pack_StdAppInfo($self->{appinfo});
        return $retval;
    }

Or as a standalone CWPDB helper class:

    use Palm::StdAppInfo;

Many Palm applications use a common format for keeping track of categories. The CWPalm::StdAppInfo class deals with this common format:

        $pdb = new Palm::PDB;
        $pdb->Load("myfile.pdb");

        @categories   = @{$pdb->{appinfo}{categories}};
        $lastUniqueID =   $pdb->{appinfo}{lastUniqueID};
        $other        =   $pdb->{appinfo}{other};

where:

CW@categories is an array of references-to-hash: The name of the category, a string of at most 16 characters. The category ID, an integer in the range 0-255. Each category has a unique ID. By convention, 0 is reserved for the Unfiled category; IDs assigned by the Palm are in the range 1-127, and IDs assigned by the desktop are in the range 128-255. A boolean. This field is true iff the category has been renamed since the last sync.

CW$lastUniqueID is (I think) the last category ID that was assigned.

CW$other is any data that follows the category list in the AppInfo block. If you're writing a helper class for a PDB that includes a category list, you should parse this field to get any data that follows the category list; you should also make sure that this field is initialized before you call CW&Palm::StdAppInfo::pack_AppInfo.

Normally, the AppInfo block includes a byte of padding at the end, to bring its length to an even number. However, some databases use this byte for data.

If your database uses the padding byte for data, then your CW&ParseAppInfoBlock method (see SYNOPSIS) should call CW&parse_StdAppInfo with a true CW$nopadding argument.

If, for whatever reason, you wish to inherit CW&StdAppInfo::ParseAppInfoBlock, then add

    use constant APPINFO_PADDING => 0;

to your handler package, to tell it that the padding byte is really data.

    &Palm::StdAppInfo::seed_StdAppInfo(\%appinfo);

Creates the standard fields in an existing AppInfo hash. Usually used to ensure that a newly-created AppInfo block contains an initialized category array:

        my $appinfo = {};

        &Palm::StdAppInfo::seed_StdAppInfo($appinfo);

Note: this is not a method.

    $appinfo = Palm::StdAppInfo->newStdAppInfo;

Like CWseed_StdAppInfo, but creates an AppInfo hash and returns a reference to it.

    $pdb = new Palm::StdAppInfo;

Create a new PDB, initialized with nothing but a standard AppInfo block.

There are very few reasons to use this, and even fewer good ones. If you're writing a helper class to parse some PDB format that contains a category list, then you should make that helper class a subclass of CWPalm::StdAppInfo.

    $len = &Palm::StdAppInfo::parse_StdAppInfo(\%appinfo, $data, $nopadding);

This function (this is not a method) is intended to be called from within a PDB helper class's CWParseAppInfoBlock method.

CWparse_StdAppInfo() parses a standard AppInfo block from the raw data CW$data and fills in the fields in CW%appinfo. It returns the number of bytes parsed.

CW$nopadding is optional, and defaults to false. Normally, the AppInfo block includes a padding byte at the end. If CW$nopadding is true, then CW&parse_StdAppInfo assumes that the padding byte is application data, and includes it in CW$appinfo{'other'}, so that the caller can parse it.

    $pdb = new Palm::StdAppInfo;
    $pdb->ParseAppInfoBlock($data);

If your application's AppInfo block contains standard category support and nothing else, you may choose to just inherit this method instead of writing your own CWParseAppInfoBlock method. Otherwise, see the example in SYNOPSIS.

    $data = &Palm::StdAppInfo::pack_StdAppInfo(\%appinfo);

This function (this is not a method) is intended to be called from within a PDB helper class's CWPackAppInfoBlock method.

CWpack_StdAppInfo takes an AppInfo hash and packs it as a string of raw data that can be written to a PDB.

Note that if you're using this inside a helper class's CWPackAppInfoBlock method, you should make sure that CW$appinfo{other} is properly initialized before you call CW&Palm::StdAppInfo::pack_StdAppInfo.

CW$nopadding is optional, and defaults to false. Normally, the AppInfo block includes a byte of padding at the end. If CW$nopadding is true, then CW&pack_StdAppInfo doesn't include this byte of padding, so that the application can use it.

    $pdb = new Palm::StdAppInfo;
    $data = $pdb->PackAppInfoBlock();

If your application's AppInfo block contains standard category support and nothing else, you may choose to just inherit this method instead of writing your own CWPackAppInfoBlock method. Otherwise, see the example in SYNOPSIS.

    $pdb->addCategory($name [, $id [, $renamed]]);

Adds a category to CW$pdb.

The CW$name argument specifies the new category's name.

The optional CW$id argument specifies the new category's numeric ID; if omitted or undefined, &addCategory will pick one.

The optional CW$renamed argument is a boolean value indicating whether the new category should be marked as having been modified. This defaults to true since, conceptually, &addCategory doesn't really add a category: it finds one whose name happens to be empty, and renames it.

Returns a true value if successful, false otherwise. In case of failure, &addCategory sets CW$Palm::StdAppInfo::error to an error message.

    $pdb->deleteCategory($name);

Deletes the category with name CW$name. Actually, though, it doesn't delete the category: it just changes its name to the empty string, and marks the category as renamed.

    $pdb->renameCategory($oldname, $newname);

Renames the category named CW$oldname to CW$newname.

If successful, returns a true value. If there is no category named CW$oldname, returns a false value and sets CW$Palm::StdAppInfo::error to an error message.

Andrew Arensburger <arensb@ooblick.com>

Palm::PDB(3)