data/TWiki/TWikiLineIteratorDotPm.txt
author Colas Nahaboo <colas@nahaboo.net>
Sat, 26 Jan 2008 15:50:53 +0100
changeset 0 414e01d06fd5
permissions -rw-r--r--
RELEASE 4.2.0 freetown
     1 ---+ Package =TWiki::LineIterator=
     2 
     3 Iterator over the lines in a file
     4 
     5 
     6 %TOC%
     7 
     8 ---++ new( $file )
     9 
    10 Create a new iterator over the given file. if the file cannot be opened, then
    11 there will be no elements in the iterator.
    12 
    13 
    14 ---++ hasNext() -> $boolean
    15 
    16 Returns false when the iterator is exhausted.
    17 
    18 <verbatim>
    19 my $it = new TWiki::ListIterator(\@list);
    20 while ($it->hasNext()) {
    21    ...
    22 </verbatim>
    23 
    24 
    25 ---++ next() -> $data
    26 
    27 Return the next line in the file.
    28 
    29 The iterator object can be customised to pre- and post-process entries from
    30 the list before returning them. This is done by setting two fields in the
    31 iterator object:
    32 
    33    * ={filter}= can be defined to be a sub that filters each entry. The entry
    34      will be ignored (next() will not return it) if the filter returns false.
    35    * ={process}= can be defined to be a sub to process each entry before it
    36      is returned by next. The value returned from next is the value returned
    37      by the process function.
    38 
    39 For example,
    40 <verbatim>
    41 my $it = new TWiki::LineIterator("/etc/passwd");
    42 $it->{filter} = sub { $_[0] =~ /^.*?:/; return $1; };
    43 $it->{process} = sub { return "User $_[0]"; };
    44 while ($it->hasNext()) {
    45     my $x = $it->next();
    46     print "$x\n";
    47 }
    48 </verbatim>
    49