Hash table inside class::struct

[phidelt1354]

How do you add a hash table to this structure?

struct header =>
{

customer => '$',
type => '$',
shares => '$'

};

I need to add a hash table to the header struct to hold a map of friend_type->friend_name. The friend_type string will represent the different friends in the flat.dat file that it will be reading from.

PAVANSYMBOL
LICURSISYMBOL
BASSISYMBOL


So for the example line below:

CUSTOMER|TYPE|SHARES|PAVANSYMBOL|LICUR...

PAVAN|F|100|COOL|MAN|GUY

The string "PAVANSYMBOL" will map to COOL, "LICURSISYMBOL" will map to MAN, etc.



I need help with the syntax of the structure and setting it up. The data will be read from a flat file.


Thanks!

 

[fishiface]

I've not used Class::Struct, but it's manual page offers

struct header => {
    customer => '$',
    type => '$',
    shares => '$',
    hashtable => '%'
  };

Does this not work for you?

Yours

fish


["]As soon as we started programming, we found to our surprise that it wasn't as easy to get programs right as we had thought. Debugging had to be discovered. I can remember the exact instant when I realized that a large part of my life was going to be spent in finding mistakes in my own programs.["]
--Maurice Wilkes, 1949

 

[phidelt1354]

That does work thank you! I am fairly new to PERL so I was having trouble declaring my hash table in the struct, the syntax to populate it, and how to print it out.

I appreciate your answer and feel free to give me any instruction on how the syntax for populating/printing fields from my hash table within the struct.

Thanks!

 

[fishiface]

my $h1 = new header; # construction

$h1->hashtable( colour => 'red' ); # assignments...
$h1->hashtable( size => 6 );
$h1->hashtable( type => 'rubber' );

print $h1->hashtable( 'type' ), "\n"; # print a value

seems to be the Class::Struct way of doing things.

I confess, I've not felt a need for this library or for formal structures since I started using perl. The language is rich enough to do all of this on the fly. That said, I don't know your application or requirements and there's no harm in the extra safety and error-checking that it offers.

Yours,

fish



["]As soon as we started programming, we found to our surprise that it wasn't as easy to get programs right as we had thought. Debugging had to be discovered. I can remember the exact instant when I realized that a large part of my life was going to be spent in finding mistakes in my own programs.["]
--Maurice Wilkes, 1949

 

[phidelt1354]

Thanks a lot Fish! I really appreciate your help!

 

[phidelt1354]

FISH! I need your help again please! How would you initialize a hash later in the code (ie not at declaration). I am getting an error that says "Use of uninitialized value in length at....."

I am calling the length function on a field in my hash that has no value so I want to initialize this. Do you know the solution to this or can anyone help?

Thanks!

 

[travs69]

why are you checking the length if you know it is empty? Maybe you need to use "exists" or something first?

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Travis - Those who say it cannot be done are usually interrupted by someone else doing it; Give the wrong symptoms, get the wrong solutions;

 

[phidelt1354]

I'm declaring my hash table that exists from within a struct. Then later in the code, the program goes through and loads a flat file to read from and it reads each line and populates each line accordingly. I am checking to see if the value exists. The problem is when I check to see if it exists by checking the length and the value DOESN'T exist, PERL gives a warning when it's running saying the value was never initialized.

SO... I want to intialize the table (not at declaration) so that it at least will have the NULL character when it comes to the 'length' check.

Thanks!