[MacPerl-Porters] here is a little (redundant) test of seek()

[Prymmer/Kahn <pvhp@best.com>]

As the subject mentions, enclosed please find a little
test script to give seek(FH,$offset,0) a fair workout on
a small generated text file.  I find that without supplying this
script with an argument that all tests fail, that is, one cannot
seek() within a file opened for writing.  However one can give an
argument and all 21 tests pass.  FWIW this is the same result I 
obtained with perl 5.005_03 on linux-ppc, so I suppose there is 
no problem with seek on MacOS perl:

#!./perl
#
# NAME
#     seek.t
# SYNOPSIS
# test seeking on open (for writing) filehandles.
# USAGE:
#     perl seek.t
#     perl seek.t close_then_reopen
# miniperl may be substituted for perl in the above usage.
#

my $data = <<'EOD';
almond
beechnut
chestnut
doughnut
elmnut
firnut
EOD

my @data=split("\n",$data);

# behavior same under MacOS miniperl 5.6.0 with either open():
#open(NUT,"+>nut-$$") or die "Could not open nut-$$: $!";
open(NUT,">nut-$$") or die "Could not open nut-$$: $!";
print NUT $data or die "Could not print data to nut-$$: $!";

if (@ARGV) { # close and re-open
    close NUT or die "Could not close nut-$$: $!:";
    open(NUT,"<nut-$$") or die "could not open nut-$$ to read: $!";
	my @read_data = (<NUT>) or die "could not read nut-$$: $!";
}

print "1..",int(@data*(@data+1)/2),"\n";

my $test = 1;
my $offset = 0;
for (my $j = 0; $j < @data; $j++) {

    # The following works at least with single character endl's (MacOS, Unix, VMS):
	
    if ($j > 0) { $offset += length($data[$j-1]) + 1; }
	
    seek NUT,$offset,0;

    for (my $i = $j; $i < @data; $i++) {
        chomp(my $datum = <NUT>);
        print +($datum ne $data[$i]) ? "not # datum is $datum; data[$i] is $data[$i] " : '', "ok $test\n";
	    $test++;
    }
}

# clean up

close NUT or warn "trouble closing nut-$$: $!";
unlink("nut-$$");
__END__

Peter Prymmer




==== Want to unsubscribe from this list?
==== Send mail with body "unsubscribe" to macperl-porters-request@macperl.org