Whenever you get errors or warnings, I suggest you look up the
perldiag manual page to see more verbose explanation. Or, you can put the
use diagnostics; line near the top of your program. This way, you let Perl explains more detail about what's wrong or what might be wrong in your program. The first is really a warning message instead of an error (indicated by "(W)", while the second is a fatal error.
Use of reference "%s" as array index
(W misc) You tried to use a reference as an array index; this probab
+ly
isn't what you mean, because references in numerical context tend to
+ be
huge numbers, and so usually indicates programmer error.
If you really do mean it, explicitly numify your reference, like so:
$array[0+$ref]. This warning is not given for overloaded objects,
either, because you can overload the numifi- cation and stringificat
+ion
operators and then you assumedly know what you are doing.
Can't call method "%s" on unblessed reference
(F) A method call must know in what package it's supposed to run. I
+t
ordinarily finds this out from the object reference you supply, but
+you
didn't supply an object reference in this case. A reference isn't a
+n
object reference until it has been blessed. See per- lobj.
The
@unsorted array contains list of objects of
GARD::Book class, when you pass it to the
sort function, the
$a and
$b variables contain references to the correspondent elements in that array. So you simply say
$a->function instead of
$unsorted[$a]->function in the sort block.
Saying $a->function in the sort block is the same with $unsorted[SOME_INDEX]->function outside the block. When you say $unsorted[$a]->function in the sort block the following (more or less) happens:
- $a becomes a reference of one of @unsorted element, which is an object of GARD::Book
- Now you're using that reference (stringified as GARD::Book=HASH(0x2b7831c)) as array index, but, usually, this is not something you want, hence the warning. Imagine that you're actually doing $unsorted["GARD::Book=HASH(0x2b7831c)"]->function instead of $unsorted[0]->function.
- The $unsorted[$a] is evaluted to some reference and used to call a method. But we need more than a mere reference to call a method, we need a blessed reference, and that's what object is all about in Perl (see the first few lines in the perlobj). That's what triggered the fatal error: unblessed reference was used to call a method.
Open source softwares? Share and enjoy. Make profit from them if you can. Yet, share and enjoy!
-
Are you posting in the right place? Check out Where do I post X? to know for sure.
-
Posts may use any of the Perl Monks Approved HTML tags. Currently these include the following:
<code> <a> <b> <big>
<blockquote> <br /> <dd>
<dl> <dt> <em> <font>
<h1> <h2> <h3> <h4>
<h5> <h6> <hr /> <i>
<li> <nbsp> <ol> <p>
<small> <strike> <strong>
<sub> <sup> <table>
<td> <th> <tr> <tt>
<u> <ul>
-
Snippets of code should be wrapped in
<code> tags not
<pre> tags. In fact, <pre>
tags should generally be avoided. If they must
be used, extreme care should be
taken to ensure that their contents do not
have long lines (<70 chars), in order to prevent
horizontal scrolling (and possible janitor
intervention).
-
Want more info? How to link
or How to display code and escape characters
are good places to start.