Re^2: Deleting duplicate lines from file

[Win]

I am in the process of trying to get this code to work. Please could someone offer me a detailed explanation of how this works so I can fix problems that I am having with it.

For example, I don't understand this line:

 my (@lines, %line_md5);

or these lines:

    my $digest = md5($_);
    unless ( exists $line_md5{$digest} ) {
      $line_md5{$digest} = 1;

[xorl]

my

unless

It looks like perldoc is down....so try these links:

my

unless (BTW does anyone know where perldoc.perl.org keeps the info about unless and other control structures?)

[turo]

You hurt me ...

program file

thats enough? ....

i recommend you to read some perl guide

[Anonymous Monk]

So how much are you getting paid for this one? How much do we get?

[blazar]

It works nearly in the same exact way as the code you already asked about except that:

1. the flow control is syntactically (but not logically!) different;
2. it doesn't do a check on the actual strings, but on a checksum computed for them which gives a sufficient condition for two of them to be different. That is, if the checksums are different, then the strings will be different too, while the converse does not hold: different strings may have the same checksums (but we rely on the confidence that such occurrencies are rare enough), hence => my remarks

Then you wrote:

For example, I don't understand this line:

 my (@lines, %line_md5);

Oh my! Please tell me you're joking!! I see that you have 204 writing as of now. That's quite surprising... maybe you're not really programming in Perl, but in some vaguely similar language. What is it precisely that you do not understand?

[Win]

The question is.

Why use

my (@lines, %line_md5);

when you can use

 my @lines; my %line_md5:

I don't really see that there is any point in grouping them together like that. I am thinking of putting a moto on my messages: Keep it simple when possible. Go complex when required.

[Anonymous Monk]

Both are simple. Concentrate on your problem

[blazar]

[slightly edited and fixed a typo: Perl 5 doesn't make that much use of the colon!] The question is my (@lines, %line_md5); when you can use  my @lines; my %line_md5;

Because it's simpler, cleaner, easier to type and to read, and groups together correlated variables maybe?

I don't really see that there is any point in grouping them together like that. I am thinking of putting a moto on my messages: Keep it simple when possible. Go complex when required.

Indeed! Just be aware that the World's concept of "complex" is not bound to match Win's authoritative one...

PS: here's a motto: "don't put motos on your messages". Oh, or... was it all about Moto? This would explain a lot of things... but no: PM is definitely about Perl.