[lug] perl question

[Ralf Mattes]

On Sun, 9 Apr 2000, Michael J. Hammel wrote:

[...]

> open(FD, $filename);
> while ( <FD> )
> {
> 	blah;
> }
> seek (FD, 0, 0);
> while ( <FD> )
> {
> 	blah;
> }
> close(FD);
> 
> Hey Tony - check me on that <FD> bit.  I'm not exactly sure what the <>
> bracketing is for.

Perl black magic ;-) The <> is a special perl construct to 
easily access text files (after all this is what perl once was
meant to do). In scalar context the <> construct will return
a line of input at a time, in array context it will return 
a list of all lines of the file referenced by the file descriptor.
BTW, the 'File descriptor' isn't really a Unix file descriptor,
it's an opaque data structure that has some 'magic' capabilities.
Once (long ago) the only way to pass an open file to a subroutine
was by passing the typeglob of the file descriptor 
(for example 'pretty_print(*MYFILE, $data);'
If you prefer a 'cleaner' approach you could do:
#!/usr/bin/perl

use IO::File;

my $file = new IO::File("/etc/passwd")
  or die "Someone removed the password file. Good luck!\n";

while (<$file>){
	....
}


  Ralf

*-------------------------------------------------------------------*
|                                     |                             |==
| Ralf Mattes                         | ralf.mattes at pyramid.de      |==
| Programming, Administration         | rm at ns.aura.de               |==
|                                     |                             |==
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