still need an ='s sign for anonymouse arrays
@hash = {'hi_there','bye_there','over_there'};
$hash{'bye_there'} = "testing";
print $hash{'bye_there'};
On Friday 09 March 2001 23:10, Sterin, Ilya wrote:
> That's a good explanation, since I myself understood everything except the
> @ usage for this expression. Now I can see, but why doesn't this work with
> my perl5.6
>
> use strict;
> my @hash{'hi_there','bye_there','over_there'};
> $hash{'bye_there'} = "testing";
> print $hash{'bye_there'};
>
> Any ideas, it comes with...
> syntax error at test.pl line 2, near "@hash{"
> Execution of test.pl aborted due to compilation errors.
>
> -----Original Message-----
> From: Matthew O. Persico [mailto:[EMAIL PROTECTED]]
> Sent: Friday, March 09, 2001 11:56 PM
> To: [EMAIL PROTECTED]
> Subject: Re: Reusable code for binding columns.
>
> "Thomas A. Lowery" wrote:
> > OK Randal, how does this work? I put it in code and see it WORKS, but my
> > brains hurts trying to understand it.
> >
> > > $rc = $sth->bind_columns(\@column{qw(one two three four five)});
>
> Step back a bit.
>
> An array element is $array[0].
>
> An array slice is @array[1,2,3,4], for example.
>
> A hash element is $hash{'hi_there'}. I know you don't NEED the quotes,
> but they make sense for the purposes of the demo.
>
> A hash slice is @hash{'hi_there','bye_there','over_there'} for example.
>
> <aside>
> As I understand it the reason that a HASH slice is defined with an ARRAY
> indicator (@) is that in this context, @ is NOT an array indicator -
> it's a LIST indicator. The type of list is defined by the brackets; []
> is an array, a list of elements, {} is a hash, a list of paired
> elements.
> </aside>
>
> Therefore, @column{'one', 'two', 'three', 'four', 'five'} is a hash
> slice, which is simply a list of the values at these keys of the hash
> %column.
>
> Typing all the quotes is a PITA, so we use the "quote word" operator to
> simplify things to
>
> @column{qw(one two three four five)}
>
> Now, according to the docs (http://www.perldoc.com/cpan/DBI.html)
>
> bind_columns
>
> $rc = $sth->bind_columns(@list_of_refs_to_vars_to_bind);
>
> Calls /bind_col for each column of the SELECT statement. The
> bind_columns method will die
> if the number of references does not match the number of fields.
>
> So, in order to get a list_of_refs, you put \ before the list. This does
> NOT create a reference to the whole list, as you'd might expect. Rather
> the "ref"-ness gets distributed to each element of the list, creating a
> list of REFs.
>
> Personally, I think this is a perfect example of the "beauty" of Perl.
> Visually, \@column{qw(one two three four five)} LOOKS like a ref of a
> list. Bit, I don't think there IS such a thing.
>
> \@foobar IS a ref of an ARRAY.
> \%baba is a ref of a HASH.
> \(1,2,3,4) is a ref of a LIST. But what's the point of that? If you want
> an ARRAY ref, you can do [1,2,3,4]. If you want a hash ref, do
> \{1,2,3,4} (or, more clearly, \{1=>2,3=>4}). A ref of a LIST is
> ambiguous, as used in this context. Therefore, it can't be used that
> way. So, I guess, it was decided that defining this construct as
> converting a list to a list of refs would be useful and therefore, it
> was done.
>
> <shameless flame-bait>
> Now, IMHO, the majority of compsci language police would end up in
> straight jackets if they tried to create a BNF for this scenario. Tough.
> Perl gets the job done w/o slavish devotion to an academic concept. Let
> Gossling, and Guido chew on that! harumph! Perl "just makes sense". It's
> as close to a DWIM language as we have today.
> </shameless flame-bait>
>
> HTH
>
> Oh, and by the way, just because I think I can explain it, don''t for
> one momment belive that I'd EVER dream that one up on my own. :-)
>
> But you shouldn't be surprised that Randal did. Remember, he's the
> author of the Schwarzian transform.
>
> --
> Matthew O. Persico
>
> http://www.acecape.com/dsl
> AceDSL:The best ADSL in Verizon area
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