Last Updated：2025/12/05
(object-oriented programming) The problematic situation where a base class contains methods which mutate an object in a manner which may invalidate a (stronger) invariant found in a derived class, violating the Liskov substitution principle. For example, if a circle is modelled as a subtype of an ellipse, and the ellipse has a method that stretches it on one axis, the circle must also implement that method despite it making no sense for a circle.
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circle-ellipse problem
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Source Word
circle-ellipse problem
Noun
(object-oriented
programming)
The
problematic
situation
where
a
base
class
contains
methods
which
mutate
an
object
in
a
manner
which
may
invalidate
a
(stronger)
invariant
found
in
a
derived
class,
violating
the
Liskov
substitution
principle.
For
example,
if
a
circle
is
modelled
as
a
subtype
of
an
ellipse,
and
the
ellipse
has
a
method
that
stretches
it
on
one
axis,
the
circle
must
also
implement
that
method
despite
it
making
no
sense
for
a
circle.
Japanese Meaning
オブジェクト指向プログラミングにおいて、基底クラスに定義されたメソッドが、派生クラスで保持される強固な不変条件を破ってしまう可能性がある設計上の問題。例えば、楕円のサブタイプとして円をモデル化した際に、楕円に備わった変形メソッドを円にも実装させる必要が生じ、円としての特性に矛盾が生じるケースを示す。
Sense（1）
(object-oriented
programming)
The
problematic
situation
where
a
base
class
contains
methods
which
mutate
an
object
in
a
manner
which
may
invalidate
a
(stronger)
invariant
found
in
a
derived
class,
violating
the
Liskov
substitution
principle.
For
example,
if
a
circle
is
modelled
as
a
subtype
of
an
ellipse,
and
the
ellipse
has
a
method
that
stretches
it
on
one
axis,
the
circle
must
also
implement
that
method
despite
it
making
no
sense
for
a
circle.
