Beefy Boxes and Bandwidth Generously Provided by pair Networks
more useful options

comment on

( #3333=superdoc: print w/replies, xml ) Need Help??

Yes, as I said, I understand the objection. I note that you don't quote what your alternative is nor acknowledge the problem that I was bringing up.

Did you give a concrete class when you asked your question? As I've said, I agree that there is a problem in theory, and that sometimes there is a problem in practice. But I've also found that, in practice, exactly what it means to get a 'new' object from an object of a *specific* class is often quite clear (and I don't think it usually means what you appear to be referring to as "clone" nor "copy").

You appear to be using "clone" to mean something close to "copy all of the object's attributes" and using "copy" (based on emphasis) to mean something close to "copy none of the object's attributes".

I don't think I've ever seen people talking about classes as having two types of attributes (that I'll define shortly). So I'm not surprised that asking questions in the abstract fail to get people to think about splitting attributes into two types. In practice, for many Perl classes, I think this split happens quite naturally.

I'll call the two types 'basis' attributes and 'convenience' attributes. The basis attributes are items that must be passed in to new(). The convenience attributes have more to do with the personal preferences of the user of the module.

$obj->new( $basis1, $basis2, ... ) creates a new object based on the passed-in basis attributes but copying the convenience attributes from $obj.

Now, some classes have attributes that don't clearly fall into one of these categories, and I suspect in that such cases the meaning of 'instance new' would not be as clear.

And I suspect that people who think $obj->new( ... ) should be "clone" are either thinking of convenience attributes or aren't thinking of the "..." part while people who think $obj->new( ... ) should do ref($obj)->new( ... ) aren't thinking of convenience attributes (that perhaps are more common in Perl OO than in other flavors of OO).

- tye        

In reply to Re^5: It's a dog, but what kind? (polymorphism , in Perl OO) (!abstract) by tye
in thread It's a dog, but what kind? (polymorphism , in Perl OO) by blue_cowdawg

Use:  <p> text here (a paragraph) </p>
and:  <code> code here </code>
to format your post; it's "PerlMonks-approved HTML":

  • Posts are HTML formatted. Put <p> </p> tags around your paragraphs. Put <code> </code> tags around your code and data!
  • Titles consisting of a single word are discouraged, and in most cases are disallowed outright.
  • Read Where should I post X? if you're not absolutely sure you're posting in the right place.
  • Please read these before you post! —
  • Posts may use any of the Perl Monks Approved HTML tags:
    a, abbr, b, big, blockquote, br, caption, center, col, colgroup, dd, del, div, dl, dt, em, font, h1, h2, h3, h4, h5, h6, hr, i, ins, li, ol, p, pre, readmore, small, span, spoiler, strike, strong, sub, sup, table, tbody, td, tfoot, th, thead, tr, tt, u, ul, wbr
  • You may need to use entities for some characters, as follows. (Exception: Within code tags, you can put the characters literally.)
            For:     Use:
    & &amp;
    < &lt;
    > &gt;
    [ &#91;
    ] &#93;
  • Link using PerlMonks shortcuts! What shortcuts can I use for linking?
  • See Writeup Formatting Tips and other pages linked from there for more info.
  • Log In?

    What's my password?
    Create A New User
    and the web crawler heard nothing...

    How do I use this? | Other CB clients
    Other Users?
    Others surveying the Monastery: (7)
    As of 2021-03-05 17:57 GMT
    Find Nodes?
      Voting Booth?
      My favorite kind of desktop background is:

      Results (114 votes). Check out past polls.