On Mon, Apr 20, 2009 at 12:26, Dermot <paik...@googlemail.com> wrote:
> 2009/4/20 Chas. Owens <chas.ow...@gmail.com>:
>> On Mon, Apr 20, 2009 at 11:21, Dermot <paik...@googlemail.com> wrote:
> ...
>>> I thought that I could say somethign
>>> like, "if %defaults, return %defaults else populate %defaults and
>>> return".
>>>
>>> Here's the error I am getting:
>>>
>>> Can't modify private hash in logical or assignment (||=) at
>>> /export/web/lib/Foo.pm line 28, near "}
>> snip
>>
>> You should have gone with your first instinct:
>>
>> sub getDefaults {
>>
>> return if %defaults;
>>
>>
>> my $sql = q{SELECT * from bar};
>> my $sth = $dbh->prepare($sql);
>> $sth->execute;
>> while (my $row = fetchrow_hashref) {
>> $defaults{$row->{id}} = $row->{'description'};
>> }
>> return
>> }
>
> Just so I'm clear because it's actually quite a hard thing to test, my
> sub should look start like this:
>
> my %defaults # Declared globally;
>
> sub getDefaults {
> return if %defaults;
> %defaults = do {...}
> }
snip
I would avoid the do {...} and just muck with %defaults directly (as I
did in the example).
snip
>> You might also want to look into the Singleton pattern[1].
>>
>> 1. http://en.wikipedia.org/wiki/Singleton_pattern
>
>
> Design patterns. I have come across this term a few times but there is
> very little Perl examples of Design Patterns around and not a single
> example of Singleton pattern on that page :-(
snip
Here you go:
http://perldesignpatterns.com/?PerlDesignPatterns
http://perldesignpatterns.com/?SingletonPattern
--
Chas. Owens
wonkden.net
The most important skill a programmer can have is the ability to read.
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