[Cedarvalley] upload problem

[Aaron Thompson]

Nice, I ran into to places this would have been useful with lists
in the last week - instead I ended up using a hash:

my %groups;
for my $group (split(" ",`id -nG $self->{_user_name}`)){$groups{$group}++;}
...

if($groups{'valid_group'}){
 #I'm a group memeber
}#fi

Your line could have been used instead:

my @groups = split(" ",`id -nG $self->{_user_name}`);
...
if({ map { $_ => 1 } @groups }->{'valid_group'}){
  #I'm a group member
}

@

On Wed, Mar 31, 2004 at 12:24:53PM -0600, Stephen D. Wells wrote:
> You probably have already seen this but I just stumbled across it, liked
> it and thought I'd pass it along...
> 
> * A one-liner for checking to see if a value exists in a list:
> if ({ map { $_ => 1 } qw(apple orange lemon) }->{apple}) {
>     # do stuff
> }
> 
> Here's what's happening:
> 
> We are creating an anonymous hash of the values in the list:
>   { apple => 1, orange => 1, lemon => 1 }
> 
> Then checking to see if that hash exists
>   { apple => 1, orange => 1, lemon => 1 }->{apple} # should return 1
> 
> This replaces code that you see all the time like this:
> my $found = 0;
> {
>  for (qw(apple orange lemon)) {
>      next unless $_ eq "apple";
>      $found++;
>      last;
>   }
> }
> if ($found) {
>    # do stuff
> }
> 
> * more complex example
> 
> I've been using the Class::DBI module for some extranet reporting
> software I created and have a table structure like so:
> 
> user	user_access	access
> ----	-----------	------
> id	id		id
> name	user_id		name
> pass	access_id
> 
> see Class::DBI for how to build your Classes
> 
> in one line I can check to see if this user is in the 'admin' group and
> allow my administration functions to override the user functions using
> the following:
> 
> if ({ map { $_->access_id->name => 1 }
> 	 (EX::DBI::User->accesses)}->{'admin'}) {
>    require "EX/Admin.pm";
>    push (@ISA, 'EX::Admin');
> }
> 
> I was kinda' impressed with the fact there it's such a compact piece of
> code.
> 
> Thoughts?
> STEVE
> 
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-- 
Aaron Thompson   Unix Systems Administrator, College of Natural Science
http://www.cns.uni.edu/~thompson/           University of Northern Iowa

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