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Re: OOP introspection (inheritance)
by LanX (Saint) on Apr 02, 2021 at 21:28 UTC
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> Is there a way to get all the hierarchy of the classes of an object? (No Moose etc,just classic OO Perl)
say A->B>C , examining C gives A and B as parents.
@ISA is a package var, i.e. globally accessible.
So start iterating over @C::ISA and continue recursively?
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Re: OOP introspection (composition)
by LanX (Saint) on Apr 02, 2021 at 21:39 UTC
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> Also in the case of composition how can I find out which class depends on which class?
That's a tougher one, because AFAIK does "classic Perl" only allow imports for "composition". Differing OO-frameworks might have differing approaches and builtin solutions for inspection.
But you can iterate over all subs in the namespace° of a class and inspect in which module it was originally defined.
There is a core module for that° Sub::Util (read the doc for subname ) ... or something like Sub::Identify from CPAN.
edit
°) This won't help you if the composition was done by changing AUTOLOAD , but I don't even know if this approach is even a thing in OOP (?)
°) sorry I was wrong about that, Sub::Util is not implementing what Sub::Identify does. But the latter comes with a compact pure Perl implementation using the B backend to extract those informations. AFAICS it's the same approach like described in the book "Perl Hacks". | [reply]
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could be that I totally misunderstood your question about composition as "composing" a class with roles
compare
https://perldoc.perl.org/perlootut#Roles
vs
https://perldoc.perl.org/perlootut#Composition °
In case you meant the latter:
This is extremely difficult in dynamically typed languages.
You would of course parse the code for use of other classes and constructors named "new".
But this would only give you a fragile approximation of dependencies at best, because of all the flexibility Perl offers.
°) which is very generally speaking and fuzzy
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Re: OOP introspection
by Discipulus (Canon) on Apr 02, 2021 at 21:30 UTC
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Re: OOP introspection
by haukex (Archbishop) on Apr 03, 2021 at 08:32 UTC
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LanX has already pointed you to @ISA. Note that if this is about method resolution order, see mro, for example it provides a mro::get_linear_isa($classname) function that may be useful.
Also in the case of composition how can I find out which class depends on which class? Or what kind of objects can be injected in the constructor of an other object?
I'm not sure I understand, could you illustrate these questions with code?
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Indeed, using mro::get_linear_isa($class) is the right way for obtaining the full class hierarchy!
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Re: OOP introspection
by perlfan (Vicar) on Apr 02, 2021 at 22:07 UTC
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I suppose one way to do it would be to go "up the chain"; utlizing SUPER (i.e., $self->SUPER::new + ref on the ancestor to get __PACKAGE__, it's reasonable to assume you could explore the turtles all the way up). Start with your initial blessed reference; recreate parent using my $father = $son->SUPER::new; use $father to recreated grandfather, so on and so forth. This example relies on each having new; but seems to reason it would work in Moo, Moose, and their elk. | [reply]
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Aside from the reliance on a predictably-named constructor (->new), this also implicitly assumes single inheritance. I'm not sure that there's any practical way to get all the ancestors in a multiple-inheritance scenario other than iterating the @ISAs.
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I didn't consider multiple inheritenace. I suppose I need to play with SUPER to see what it does in that case.
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perlfan:
If the system allowed additional upvodes, I'd give an extra one just for that last word. ;^)
...roboticus
When your only tool is a hammer, all problems look like your thumb.
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Re: OOP introspection
by hippo (Bishop) on Apr 03, 2021 at 10:21 UTC
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I'm trying to get my head around the complexity of the huge XML::Compile namespace.
Like I wanted to change the connection timeout from the default to 10 seconds.
So there's XML::Compile::Transport::SOAPHTTP which does that,but then I was trying to figure out how that relates to the main XML::Compile::WSDL11
when doing the actual call with
my $call = $wsdl->compileClient('GetStockPrice', ...);
# at "run-time", call as often as you want (fast)
my $answer = $call->(%request);
how does the XML::Compile::Transport::SOAPHTTP relates to this call?How should I use it?
eventually after sometime I used
my $trans = XML::Compile::Transport::SOAPHTTP
->new(timeout => 500, address => $wsdl->endPoint);
$wsdl->compileCalls(transport => $trans);
# alternatives for simple cases
$wsdl->compileAll('CALLS');
$wsdl->compileAll;
my $answer = $wsdl->call($myop, $request);
and not using compileClient.
but the point is, can I rely to something else than the documentation? Would introspection be useful in this case?
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