Hi Marco,
see below for my response.
On Thu, 18 Jun 2015 15:17:27 +0200
Marco <ma...@marcobaldo.ch> wrote:
> Hello.
>
> I need some help in understanding why the first
>
> my ($Count,$Saw)=$self->{_Portobj}->read(1);
>
> is executed without any problem , however the second identical statement
> inside the while loop fails with the error
>
> Can't call method "read" on an undefined value at wt800.pm line 121
>
The problem is that you misspelled "_Portobj" as "_PortObj". This is easier to
catch if you use accessors:
* http://perl-begin.org/tutorials/bad-elements/#accessing_object_slots_directly
> The idea behind this coding is to be able to use any object providing a
> "write" and a "read" method inside my object. (i.e.
> messageDevice::SerialPort)
>
> I'm using Perl 2.7 on a OpenSuSE 13.2 system.
>
What do you mean by "Perl 2.7"? We're way past both Perl 2 and Perl 5.002.
> Any hint?
>
> Tnx
>
> Marco
>
Some more comments on your code:
>
> sub get_answer {
>
> my ($self,$Orig_ref) = @_;
>
I personally don't like the "$Orig_ref" identifier style. "$orig_ref" or less
preferably "$origRef" are better.
> print $self,"\n";
>
> my $stat=$self->{_Portobj}->write("aaaa") or die "pippo";
> my ($Count,$Saw)=$self->{_Portobj}->read(1);
>
You need some whitespace here (before/after the "=", etc.)
> my $Count=9999;
> my $Saw="";
> my @Resp;
>
> print $self,"\n";
>
> while (($Saw == chr(10)) or ($Count == 0)) {
$Saw == chr(10) should probably be "$Saq eq chr(10)".
> print $self,"\n";
> my ($Count,$Saw)=$self->{_PortObj}->read(1); # will read
> 1 char
Misspelling here.
> push(@Resp,ord($Saw));
Missing whitespace.
> print ord $Saw,"\n";
> }
>
> }
>
> _Portobj is initialized in myObject as:
>
> sub new {
>
> my $class = shift;
> my $Tpobj = shift;
>
> my $self = {
> _Portobj => $Tpobj,
> ....
>
You could separate the identifiers' components using underscores.
> And the main () is
>
> my $PortObj = new Device::SerialPort ($Portname, $Quiet)
> or die "Can't open device $Portname: $!\n";
>
> my $Object = new myObject($Portobj);
>
Indirect object notation:
http://perl-begin.org/tutorials/bad-elements/#indirect-object-notation
Regards,
Shlomi Fish
(NOTE: perl-begin.org is a site I initiated and maintain)
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