Hi Gonzalo,
On 7 Jun., 21:25, Gonzalo Tornaria <[email protected]> wrote:
> What is the base class that one is supposed to use instead of ParentWithBase?
I think it is Parent. The Parent.__init__ accepts an argument base.
Here is a small example:
from sage.structure.parent import Parent
from sage.structure.element import Element
class MyElement(Element):
def __init__(self,n,parent):
Element.__init__(self,parent)
self.n = n
def _repr_(self):
return repr(self.n)
class MyParent(Parent):
Element = MyElement
def __init__(self,B):
from sage.all import Sets
Parent.__init__(self,base=B, category=Sets())
def _repr_(self):
return "Parent over %s"%self.base()
And if you attach that code, then you can do
sage: P = MyParent(QQ)
sage: P
Parent over Rational Field
sage: P.base()
Rational Field
As you see, the base() method exists and works correctly.
As for element constructor, in my minimal example I just provide a
class as an attribute called "Element" to the parent class. Then, an
element constructor is correctly inferred (that's one reason to
initialise the category of the parent):
sage: P(3)
3
sage: type(_)
<class '__main__.MyParent_with_category.element_class'>
sage: isinstance(P(3),MyElement)
True
sage: P._element_constructor_??
Type: instancemethod
...
def _element_constructor_from_element_class(self, *args,
**keywords):
"""
The default constructor for elements of this parent
I hope that answers your question.
Best regards,
Simon
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