On 22/08/12 22:31, Evan Driscoll wrote:
On 08/22/2012 02:45 PM, lipska the kat wrote:
On 22/08/12 20:03, Evan Driscoll wrote:
Second, this concept isn't *so* unfamiliar to you. If I give you the
following Java code:
void foo(Object o) { ... }
looking at this method declaration I can see that the method takes an
argument of type Object (and just FYI class Object is not abstract and
you can do Object o = new Object()) and does not return a value.
I know that for the lifetime of this JVM, whatever o turns out to be it
will always be an Object. I can't assign a primitive to o as ints chars
floats etc are certainly not Objects. There are certain invariants that
give me a warm and comfortable feeling inside.
I'm not saying it's nothing, but "can't assign a primitive" isn't much
of an invariant in the broad scheme of things
Well we don't want to turn this into a language comparison thread do we,
that might upset too many people but I can't remember ever writing a
method that took an Object as argument, you just can't do that much with
an Object. I do however often write methods that take an interface as
argument knowing that in future, any classes I write that implement this
interface would just work thanks to subtype polymorphism
A method 'declaration' such as this in an interface
Product getProductByBarcode(Barcode b) throws CrappyProductException;
tells me a whole lot about what the 'definition' in an implementing
class might do, in fact I might well get away with just reading the
interface and using the method without having to delve into the code.
And I think this is the nub of the problem at the moment. I'm in a
particular mindset, almost 'locked in' you might say and when I see a
Python function that doesn't give me what I need straight away I get
annoyed.
I will get over it.
when you can pass items as
diverse as lists, GUI buttons, files, etc. I would say it's more like if
you see 'int x' then *that* imposes a pretty big invariant, but passing
'Object' imposes almost nothing.
Well you may be able to pass them in but you couldn't really do anything
meaningful with them as you are restricted to operations on Object, I
suppose you could pepper your code with tests to check the runtime type
of a reference but it all gets a bit messy.
[snip]
Thus *all*
Python variables are essentially references.)
That makes sense
Thanks for taking the time to reply. It really is most valuable to me.
lipska
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Lipska the Kat©: Troll hunter, sandbox destroyer
and farscape dreamer of Aeryn Sun
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