| Subject: | FILENAME parameter has no effect. |
Frankly, FILENAME parameter is not documented. Anyway, it is lack of documentation and error. Let us look at _param function usage in Text/Template.pm:
$ grep '_param(' Template.pm
my $stype = uc(_param('type', %a) || "FILE");
my $source = _param('source', %a);
my $untaint = _param('untaint', %a);
my $prepend = _param('prepend', %a);
my $alt_delim = _param('delimiters', %a);
my $broken = _param('broken', %a);
my $delims = _param('delimiters', %fi_a);
my $fi_varhash = _param('hash', %fi_a);
my $fi_package = _param('package', %fi_a) ;
_param('broken', %fi_a) || $fi_self->{BROKEN} || \&_default_broken;
my $fi_broken_arg = _param('broken_arg', %fi_a) || [];
my $fi_safe = _param('safe', %fi_a);
my $fi_ofh = _param('output', %fi_a);
my $fi_filename = _param('filename') || $fi_self->{FILENAME} || 'template';
my $fi_prepend = _param('prepend', %fi_a);
my $package = _param('package', @_);
Note: the function 15 times is called with TWO arguments, and only once it is called with ONE argument:
my $fi_filename = _param('filename') || $fi_self->{FILENAME} || 'template';
Looking at _param definition:
sub _param {
my $kk;
my ($k, %h) = @_;
for $kk ($k, "\u$k", "\U$k", "-$k", "-\u$k", "-\U$k") {
return $h{$kk} if exists $h{$kk};
}
return;
}
it is clear that function must be called with TWO arguments. Being called with one argument if will always return undef.
Problem line again (at Template.pm line 257):
my $fi_filename = _param('filename') || $fi_self->{FILENAME} || 'template';
It should be written as
my $fi_filename = _param('filename', %fi_a) || $fi_self->{FILENAME} || 'template';
like lines just above:
my $fi_safe = _param('safe', %fi_a);
my $fi_ofh = _param('output', %fi_a);
Being fixed in such a way, FILENAME parameter works as expected.
Please note that parameter is not documented bu should be. Usage case is simple: caller code (for any reason) can read the template from a file, and so (because file is already read) use fill_in_string function (or its functional analogs) to process the template. If any program fragment is broken, error messages will look like
... at template line N
Caller code knows the file name and could specify it:
$result = fill_in_string( $template, FILENAME => 'file.txt' );
to make error messages better:
... at file.txt line N
Unfortunately, FILENAME parameter has no effect now.