[Stefan Krah] Nice, this also needs to be resolved, probably on the NumPy side:
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XND meeting
March 22nd, 2019 from 9:00 AM to 10:00 AM GMT-0400
Recurring
[Sameer Deshmukh] Can someone please explain the possible cause of this error: util.c:140: internal error: invalid value?
It happens during the GC sweep phase in Ruby, and I'm not able to understand whether this is due to premature deallocation or something else, because line 140 in util.c uses a switch-case statement utilizing a pointer to an ndt.
ndtype(float * float * float [m/s]) or similar
>>> x = xnd([[[1], [2,3]], [[4], [5,6]]])
>>> y = x[:, 0]
>>> y
xnd([[1], [4]], type='var * var * int64')
>>> print(y.type.ast_repr())
VarDim(
VarDimElem(
VarDim(
Int64(access=Concrete, ndim=0, datasize=8, align=8, flags=[]),
offsets=[0, 1, 3, 4, 6],
slices=[],
itemsize=8,
access=Concrete, ndim=1, datasize=48, align=8, flags=[]
),
index=0,
offsets=[0, 2, 4],
slices=[],
itemsize=8,
access=Concrete, ndim=2, datasize=48, align=8, flags=[]
),
offsets=[0, 2],
slices=[0:9223372036854775807:1],
itemsize=8,
access=Concrete, ndim=3, datasize=48, align=8, flags=[]
)[Stefan Krah] @wolfv ndtypes two ways:
1) Named type constructors:
>>> ndt("Velocity(float32)")
ndt("Velocity(float32)")
>>>
>>> ndt("Velocity(float32)") == ndt("float32")
False2) Typedefs:
>>> typedef("velocity", "float32")
>>> ndt("velocity")
ndt("velocity")
>>> ndt("velocity") == ndt("float32")
False[Stefan Krah] One could allow special characters in typedefs, this is currently not possible:
>>> typedef("m/s", "float32")
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
ValueError: invalid character in typedef: '/'But there's no fundamental reason.
XND#serialize function is an instance method and not a class method like that in NDT? For me its quite counter intuitive to see that it modifies self according to the value of the serialized string that it is passed. Might it not be better to implement it as a class method?
[Stefan Krah] Do you mean deserialize? It is a class method:
"deserialize", (PyCFunction)pyxnd_deserialize, METH_O|METH_CLASS, NULL },
In Python you can also call class methods from instances, but the instance is not modified:
>>> x = Decimal("1.23")
>>> y = x.from_float(100)
>>> x
Decimal('1.23')
>>> y
Decimal('100')[Sameer Deshmukh] @stefan.krah question about NDT object deallocation:
You said that reducing the refcount of a NDT object 0 via ndt_decref is supposed to be the only way of deallocating an NDT struct.
However in the python code I can see that you simply point to the default PyObject_del for the deletion (without decreasing refcount). Can you please explain why this is so?
[Stefan Krah] .tp_free = PyObject_Del is just the counterpart to self = (NdtObject *)type->tp_alloc(type, 0)
It allocates and frees the *Python object structure*.
.tp_dealloc = (destructor) ndtype_dealloc is the part that deallocates the ndt struct by calling ndt_decref().