hhalpin has asked for the wisdom of the Perl Monks concerning the following question:

Sorry about first post!

I'm no perl pro - so _please_ help me with this question. How does one create a list of structs that contain a list of structs? Or even a struct that contains a list of structs? This code doesn't work and I don't know why: 

use Class::Struct;

struct DiscourseSegment =>
{
    intonation_step=>'$',
    speed_step=>'$',
    fluctuation_step=>'$',           
    phrasenumber=>'$',               #total number of phrases
    p => '@',                     #these should be of type Phrase
};

struct Phrase =>
{    
    text => '$',
    marking => '$',    # 1 = SBEG, 2 = SF
    intonation => '$', #the level of intonation
    speed => '$',
    fluctuation => '$'
};

$ds = ();
$j = 0;
$ds = DiscourseSegment->new();
$ds->p(["hey","you"]); 
@temp = $ds->p(0);
print "*" x 30;
$temp2 = $temp[0];
print "$temp2";

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It won't print anything! I think it must be some syntactic error, but from the O'Reilly books I have it looks like it's correct. This shouldn't be too difficult :)I would also eventually want DiscourseSegment to be a list too.

Hhalpiin

P.S. - If perlmonks doesn't automatically do this, please e-mail me your response. Thanks! It will never print "hey you"

Replies are listed 'Best First'.
(crazyinsomniac) Re: How to use a list of structs that contain a list of structs?
by crazyinsomniac (Prior) on Sep 17, 2000 at 06:38 UTC
    On your code,

    The documentation says:

    Giving a struct element a class type that is also a struct is how structs are nested. Here, timeval represents a time (seconds and microseconds), and rusage has two elements, each of which is of type timeval. 

        use Class::Struct;

    struct( rusage => {
        ru_utime => timeval,  # seconds
        ru_stime => timeval,  # microseconds
    });


    struct( timeval => [
        tv_secs  => '$',
        tv_usecs => '$',
    ]);

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    start_update:
        # create an object:
    my $t = new rusage;
    # $t->ru_utime and $t->ru_stime are objects of type timeval.


    # set $t->ru_utime to 100.0 sec and $t->ru_stime to 5.0 sec.
    $t->ru_utime->tv_secs(100);
    $t->ru_utime->tv_usecs(0);
    $t->ru_stime->tv_secs(5);
    $t->ru_stime->tv_usecs(0);

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    end_update:
    Notice the notation:
    struct(struct_name => {element => element_type});

    You're missing the parentheses.

    And as for emailing you our responses, an email address would be useful. The one you entered when you registered is kept private.

    As for adamsj's comment, I think a /msg should've sufficed.

     

    "cRaZy is co01, but sometimes cRaZy is cRaZy".
                                                          - crazyinsomniac
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      Parenthesis don't matter here. struct is a function, and since Perl doesn't particularly care whether parenthesis exist in cases like this, his method will work just fine, and, IMO, is more readable. Think of => as a comma and pretend 'DiscourseSegment' is in quotes and things start to look normal from a syntax point of view.
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Re: How to use a list of structs that contain a list of structs?
by Fastolfe (Vicar) on Sep 18, 2000 at 05:51 UTC
    I don't believe you can set the value of 'p' here in one call: 
    $ds->p([ "hey", "you" ]);    # Wrong

$ds->p(0, "hey");            # Sets element 0 and
$ds->p(1, "you");            # Sets element 1; OR:

$ds = new DiscourseSegment ( p => [ "hey", "you" ] );
                             # Sets both at object creation time

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    Note that I'm only saying it's wrong because it doesn't seem to be working for me either. The documentation for Class::Struct never seems to indicate that you can set @ types as you're attempting, though I would agree it is a logical way to do it. The docs only mention the two methods I describe above.
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Re: How to use a list of structs that contain a list of structs?
by adamsj (Hermit) on Sep 17, 2000 at 01:08 UTC
    If you'll put your code inside a <CODE> block, you'll be much likelier to get a useful answer.

    Update: I see you did so--thank you!

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