Question regarding perl subroutine

[sureshsmr]

Dear Monks,

I need some advise to fix the error I am getting while running a perl code with a subprogram. Here is the perl sub program :

sub CREATE_GLOBAL_PTF_VIA_PTFMGR {
    my $pnum = (@_[0]);   ##part number passed arg @_ into local var p
+num
    my $coreid = (@_[1]);
    #use XML::Simple;
    #use HTTP::Response;
    #use LWP::UserAgent;
    my $ptfmgr_server= "v02k603.am.mot.com:9090/pcs/";
    ############## Call to PTF web services for description informatio
+n #############
    
    my $url = "http://$ptfmgr_server/services/GenerateGlobalPtf?coreid
+=$coreid&partNumber=$pnum";
    my $ua= new LWP::UserAgent;
    #my $ua->agent("Mozilla/5.0");
    my $ua->agent("");
    my $request = new HTTP::Request GET => "$url";
    my $response = $ua->request($request);
    my $ptf_filename;
    my $log = ""
    if ( $response->is_success ) {
        my $content= $response->content;
        #print "\$content = $content\n";
        ############## Read XML information #############
        my $xml = new XML::Simple(suppressempty => ''); ### create obj
+ect suppressempty returns empty elements as strings.
        my $data =  $xml->XMLin($content);         ### read XML file
        my $return_value = $data->{ReturnValue};
        my $ptfmgr_error = $data->{Error};
        my $ptf_filename = $data->{PtfFileName};
        #print "\$return_value = $return_value\n";
        #if ( $return_value == "1" ) {
        #    my $log = "\sGlobal PTF generation to \"$ptf_filename\" w
+as successful.\n";
        #} else {
        #      my $log = "\sPTFMGR returned the error:\n\n$ptfmgr_erro
+r\n\nGlobal PTF not created for $ptf_filename.\n.";
        #}
    #} else {
        #    my $log = "\sCould not create PTF via PTFMGR! It may be o
+ffline.\n";
        #    }
    
    } 
    return $ptf_filename;
}

This is the error I get while running it:

/usr/local/bin/perl PtfSapGetSyncStg.pl
syntax error at PtfSapGetSyncStg.pl line 164, near ") {"
Global symbol "$ptf_filename" requires explicit package name at PtfSap
+GetSyncStg.pl line 184.
syntax error at PtfSapGetSyncStg.pl line 185, near "}"
Execution of PtfSapGetSyncStg.pl aborted due to compilation errors.
v02k603:/edatools/served/pcs/ptfwes>

The syntax looks ok to me. May be the error is due to something else. I am running this on a unix server. Look forward to your advice. Thanks in advance, Yours Suresh

[davies]

Have a look at the line my $log = "". There's no trailing semicolon. The current poll (My most common answer to a question about Perl is:) is relevant.

Regards,

John Davies

[sureshsmr]

Hi John Davies, Thanks a lot! That was good catch. Now I am getting a different error as below:

/usr/local/bin/perl PtfSapGetSyncStg.pl
Can't call method "agent" on an undefined value at PtfSapGetSyncStg.pl
+ line 158.

Here is the code on line 158:

my $ua->agent("Mozilla/5.0");
#my $ua->agent("");

is the syntax for calling "agent" method ok? I am not sure what tool is on our unix server. Any suggestions ? Thanks Suresh

[afoken]

$ua is not what you think. It is undefined, probably because the code above lacks error checks. See Basic debugging checklist.

Alexander

[davies]

No, that syntax cannot be right. Looking at the code you posted originally, I see:

my $ua= new LWP::UserAgent;
#my $ua->agent("Mozilla/5.0");
my $ua->agent("");

You seem to be trying to use strict;, which is good (see my home node), but without understanding what it does. PerlIntro (http://perldoc.perl.org/perlintro.html#Variable-scoping) has a section on variable scoping that it might help you to understand. my creates a new instance of a variable. You may have seen examples of messages telling you that a declaration masks a previous declaration. This is telling you that you have re-initialised a variable name, which is unlikely to be what you want. I think what you want is something like:

my $ua= new LWP::UserAgent;
$ua->agent("Mozilla/5.0");

but as I don't even know what LWP is, this is a pretty wild guess. http://search.cpan.org/~gaas/libwww-perl-6.04/lib/LWP/UserAgent.pm might be another good read.

Regards,

John Davies

[monsoon]

my $ua = LWP::UserAgent->new;
$ua->agent('Mozilla/5.0');

see LPW::UserAgent

[AnomalousMonk]

    my $ptf_filename;
    ...
    if ( $response->is_success ) {
        ...
        my $ptf_filename = $data->{PtfFileName};
        ...
    } 
    return $ptf_filename;

There's another problem of masking lexical variable names similar to the one with the  $ua scalar. The first definition of  $ptf_filename before the if-block is masked by another definition of a lexical of the same name within the block. After the if-block, the value of the first lexical (which has never been given any value) is returned. (Technically, I guess this is not a masking problem but a scoping problem, as davies has alluded. It may – or may not – be perfectly valid semantically to define a lexical variable in one scope that has the same name as another lexical in a different scope. See Coping with Scoping.)

Update: Had you been using warnings in the code posted originally, Perl would have warned you about the  $ua problem (this really is a masking problem).

>perl -wMstrict -le
"my $x = 1;
 my $x;
 print $x;
"
"my" variable $x masks earlier declaration in same scope at ...
Use of uninitialized value $x in print at ...