On Fri, 25 Nov 2011 10:50:01 +0100
timothy adigun <2teezp...@gmail.com> wrote:
> Hi Mike D,
> Some comments on your codes:
> Mike D <ekimduna...@gmail.com> wrote:
>
> > Considering the following code, are all my comments correct?
> >
> > # this function expects an array to be passed by reference
> > sub foo
> > {
> > my ($thing1) = @_; # make a lexical variable for the array being passed
> >
>
> Fine, but since you are getting a reference, I don't really think you need
> the "()"
> around $thing1, which gives a list context, with one element.
> Better put:
> my $thing1=shift @_;
«my ($thing1) = @_;» is OK. «my $thing1 = @_;» is not OK, as it will take
scalar(@_); which is the number of elements in it. «my $thing1 =
shift(@_);» (or «my $thing1 = shift;» for short) does something a bit different
and changes @_.
>
>
> > for (@$thing1) # to access the whole array after referencing
> >
> for clarity use: for (@{$thing1}){...}
It's not clearer, but both forms are equivalent.
>
> > {
> > print $_."\n";
> > }
> > print $thing1->[0]."\n"; # access single element in referenced array
> > }
> >
> > my @array = (1,2,3,4);
> >
> my $array=[qw(1 2 3 4)];
>
> > foo(\@array); # pass @array by reference to sub foo
> >
> foo ($array);
You shouldn't call a scalar "$array" because it's confusing. It could be
"$array_ref". And defining a @array and taking a reference to it is a valid
strategy.
>
> your comments are ok, and may I say you should check out
> perlreftut by typing * perldoc perlreftut * on your terminal [without the
> stars], and if you will prefer to read the short tutorial as html file,
> then you can type this on your terminal:
> perldoc -oHTML -dreftutorial.html perlreftut
> I believe this will help out alot.
>
> >
> > It's pretty confusing, especially since BP uses prototypes during the
> > example, which I'm told are bad? Never use them?
> >
>
> Please, you can take time out to check on these links:
>
> http://docstore.mik.ua/orelly/perl/prog3/ch06_04.htm,
> http://docstore.mik.ua/orelly/perl/cookbook/ch10_12.htm ,
> https://www.socialtext.net/perl5/prototype,
> http://www.modernperlbooks.com/mt/2009/08/the-problem-with-prototypes.html
>
The first two links are to pirated copies of O'Reilly books.
Regards,
Shlomi Fish
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