Hi people,
I just discovered that Elixir has a "feature" I didn't know of: an
entity will inherit its parent options (in fact all statements) *if*
that entity has no statement (of *any* kind) itself. This case wasn't
relevant with the old "statement-based" syntax, since all real-life
entities had at least one field and hence at least one statement. Now,
with the new "attribute"-based syntax, this is much more relevant
since the attributes are not (do not "count" as) statements.
So, for example, with the following entities,
class A(Entity):
using_options(tablename="a", order_by="name")
name = Field(String(20))
class B(A):
data = Field(String(20))
B will inherit from A's options, setting the tablename to "a" and the
order_by to "name". The tablename doesn't cause any problem in this
case since we (luckily) have single-table inheritance by default, so
the child Entity's fields will be stored in the parent table anyway.
The fact that the order_by options is inherited seem pretty logical in
this case (even if this particular example will fail, due to an
unrelated bug I also just discovered).
So, basically I wonder what I should do about it:
- keep the feature "as-is" and just document it.
- expand the feature so that options are inherited even if the child
class set some options (obviously if they set an option which is also
set in the parent, that option get overridden). This might be nice as
I find in my models than more often than not an option which apply on
a parent, also applies to its child. By the way, this would be the
behavior we'd have if we had chosen to set option via special class
attributes (like __tablename__ = ...).
- remove that "feature" entirely. This is probably the safest bet.
- only allow option inheritance for some options and not others. This
might be too confusing, but without this, you couldn't set some
options (like tablename) on the parent without setting it on the
child.
Note that this also applies to the using_mapper_options and
using_table_options statements.
Any thoughts?
--
Gaëtan de Menten
http://openhex.org
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