More object questions...

Simon Glover

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Feb 25, 2004, 1:51:09 PM2/25/04

to Dan Sugalski, perl6-i...@perl.org

Currently, calling get_integer on a ParrotClass returns the attribute
count, so you can do:

newclass P1, "Foo"
addattribute P1, "foo_i"
addattribute P1, "foo_j"
set I1, P1
print I1

and the code will print '2'. Will this be part of the new API, or is it
simply a relic of the previous implementation.

Similarly, calling get_integer_keyed_str with a fully-qualified attribute
name returns the attribute offsets, meaning that this:

newclass P1, "Foo"
addattribute P1, "foo_i"
addattribute P1, "foo_j"
set I2, P1["Foo\x00foo_j"]
print I2

prints '1' -- is this part of the API or not?

Finally, a number of the current tests seem to rely on being able to
set and get attribute values with the syntax:

set P2["Foo\x00i"], 10
set P3["Foo\x00i"], 20
set I2, P2["Foo\x00i"]
set I3, P3["Foo\x00i"]

(where P2, P3 are objects of class Foo, and Foo has an attribute i).
Is this part of the API?

Simon

Dan Sugalski

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Feb 25, 2004, 2:03:36 PM2/25/04

to Simon Glover, perl6-i...@perl.org

At 1:51 PM -0500 2/25/04, Simon Glover wrote:
> Currently, calling get_integer on a ParrotClass returns the attribute
> count, so you can do:
>
> newclass P1, "Foo"
> addattribute P1, "foo_i"
> addattribute P1, "foo_j"
> set I1, P1
> print I1
>
> and the code will print '2'. Will this be part of the new API, or is it
> simply a relic of the previous implementation.

Relic.

> Similarly, calling get_integer_keyed_str with a fully-qualified attribute
> name returns the attribute offsets, meaning that this:
>
> newclass P1, "Foo"
> addattribute P1, "foo_i"
> addattribute P1, "foo_j"
> set I2, P1["Foo\x00foo_j"]
> print I2
>
> prints '1' -- is this part of the API or not?

Relic.

> Finally, a number of the current tests seem to rely on being able to
> set and get attribute values with the syntax:
>
> set P2["Foo\x00i"], 10
> set P3["Foo\x00i"], 20
> set I2, P2["Foo\x00i"]
> set I3, P3["Foo\x00i"]
>
> (where P2, P3 are objects of class Foo, and Foo has an attribute i).
> Is this part of the API?

Relic.

In all these cases the object will ultimately do a method lookup to
see if it has a method in place to do the operation, so you can
substitute an object for any other sort of PMC. Attribute access
should be only through the attribute API.
--
Dan

--------------------------------------"it's like this"-------------------
Dan Sugalski even samurai
d...@sidhe.org have teddy bears and even
teddy bears get drunk

Simon Glover

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Feb 25, 2004, 2:21:02 PM2/25/04

to Dan Sugalski, perl6-i...@perl.org

(You're probably getting sick of these by now...)

Should asking for a non-existant attribute cause Parrot to throw an
exception. Currently, it doesn't seem to be able to make up its mind
-- this:

newclass P1, "Foo"
find_type I0, "Foo"
new P2, I0
getattribute P3, P2, -2
getattribute P3, P2, -1
getattribute P3, P2, 0
getattribute P3, P2, 1
end

completes silently, but if we ask for an attribute with an offset >= 2
or <= -3, we get an "Array index out of bounds!" exception. Which is the
correct behaviour?

(Incidentally, I get the same behaviour with setattribute).

Simon

Dan Sugalski

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Feb 26, 2004, 8:07:31 AM2/26/04

to Simon Glover, perl6-i...@perl.org

At 2:21 PM -0500 2/25/04, Simon Glover wrote:
> (You're probably getting sick of these by now...)
>
> Should asking for a non-existant attribute cause Parrot to throw an
> exception. Currently, it doesn't seem to be able to make up its mind

[snip]

> but if we ask for an attribute with an offset >= 2
> or <= -3, we get an "Array index out of bounds!" exception. Which is the
> correct behaviour?

That was a problem with array wraparound -- I put in checking code
for this, FWIW.