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=head2 writefile

Justification:

Perl needs three or four operations to make a file out of a string:

 open my $FILE, '>', $filename  or die $!;
 print $FILE $text;
 close($FILE);

This is way simpler:

 writefile($filename,$text);

Sub writefile opens the file i binary mode (C<binmode()>) and has two usage modes:

B<Input:> Two arguments

B<First argument> is the filename. If the file exists, its overwritten.
If the file can not be opened for writing, a die (a croak really) happens.

B<Second input argument> is one of:

=over 4

=item * Either a scaler. That is a normal string to be written to the file.

=item * Or a reference to a scalar. That referred text is written to the file.

=item * Or a reference to an array of scalars. This array is the written to the
 file element by element and C<< \n >> is automatically appended to each element.

=back

Alternativelly, you can write several files at once.

Example, this:

 writefile('file1.txt','The text....tjo');
 writefile('file2.txt','The text....hip');
 writefile('file3.txt','The text....and hop');

...is the same as this:

 writefile([
   ['file1.txt','The text....tjo'],
   ['file2.txt','The text....hip'],
   ['file3.txt','The text....and hop'],
 ]);

Automatic compression:

 writefile('file.txt.gz','my text is compressed by /bin/gzip before written to the file');

Extentions C<.gz>, C<.bz2> and C<.xz> are recognized for compression. See also C<readfile()> and C<openstr()>.

B<Output:> Nothing (for the time being). C<die()>s (C<croak($!)> really) if something goes wrong.

=cut

#todo: use openstr() as in readfile(), transparently gzip .gz filenames and so on
sub writefile {
    my($filename,$text)=@_;
    if(ref($filename) eq 'ARRAY'){
	writefile(@$_) for @$filename;
	return;
    }
    open(WRITEFILE,openstr(">$filename")) and binmode(WRITEFILE) or croak($!);
    if(!defined $text or !ref($text)){
	print WRITEFILE $text;
    }
    elsif(ref($text) eq 'SCALAR'){
	print WRITEFILE $$text;
    }
    elsif(ref($text) eq 'ARRAY'){
	print WRITEFILE "$_\n" for @$text;
    }
    else {
	croak;
    }
    close(WRITEFILE);
    return;
}

=head2 readfile

Just as with L</writefile> you can read in a whole file in one operation with C<readfile()>. Instead of:

 open my $FILE,'<', $filename or die $!;
 my $data = join"",<$FILE>;
 close($FILE);

This is simpler:

 my $data = readfile($filename);

B<More examples:>

Reading the content of the file to a scalar variable: (Any content in C<$data> will be overwritten)

 my $data;
 readfile('filename.txt',\$data);

Reading the lines of a file into an array:

 my @lines;
 readfile('filnavn.txt',\@lines);
 for(@lines){
   ...
 }

Note: Chomp is done on each line. That is, any newlines (C<< \n >>) will be removed.
If C<@lines> is non-empty, this will be lost.

Sub readfile is context aware. If an array is expected it returns an array of the lines without a trailing C<< \n >>.
The last example can be rewritten:

 for(readfile('filnavn.txt')){
   ...
 }