Deprecate is_SymmetricFunction

src/sage/combinat/sf/classical.py

@@ -155,7 +155,7 @@ def _element_constructor_(self, x):
  ##############
  # Dual bases #
  ##############
- elif sfa.is_SymmetricFunction(x) and hasattr(x, 'dual'):
+ elif isinstance(x, sfa.SymmetricFunctionAlgebra_generic.Element) and hasattr(x, 'dual'):
  # Check to see if it is the dual of some other basis
  # If it is, try to coerce its corresponding element
  # in the other basis

src/sage/combinat/sf/sfa.py

@@ -304,12 +304,20 @@ def is_SymmetricFunction(x):
  sage: from sage.combinat.sf.sfa import is_SymmetricFunction
  sage: s = SymmetricFunctions(QQ).s()
  sage: is_SymmetricFunction(2)
+ doctest:warning...
+ DeprecationWarning: The function is_SymmetricFunction is deprecated;
+ use 'isinstance(..., SymmetricFunctionAlgebra_generic.Element)' instead.
+ See https://github.com/sagemath/sage/issues/38279 for details.
  False
  sage: is_SymmetricFunction(s(2))
  True
  sage: is_SymmetricFunction(s([2,1]))
  True
  """
+ from sage.misc.superseded import deprecation
+ deprecation(38279,
+ "The function is_SymmetricFunction is deprecated; "
+ "use 'isinstance(..., SymmetricFunctionAlgebra_generic.Element)' instead.")
  return isinstance(x, SymmetricFunctionAlgebra_generic.Element)
 
 #####################################################################
@@ -3429,7 +3437,7 @@ def plethysm(self, x, include=None, exclude=None):
 
  tHA = HopfAlgebrasWithBasis(R).TensorProducts()
  tensorflag = Px in tHA
- if not is_SymmetricFunction(x):
+ if not isinstance(x, SymmetricFunctionAlgebra_generic.Element):
  if R.has_coerce_map_from(Px) or x in R:
  x = R(x)
  Px = R

src/sage/rings/lazy_series.py

@@ -6981,9 +6981,8 @@ def functorial_composition(self, *args):
  """
  if len(args) != self.parent()._arity:
  raise ValueError("arity must be equal to the number of arguments provided")
- from sage.combinat.sf.sfa import is_SymmetricFunction
- if not all(isinstance(g, LazySymmetricFunction)
- or is_SymmetricFunction(g)
+ from sage.combinat.sf.sfa import SymmetricFunctionAlgebra_generic
+ if not all(isinstance(g, (LazySymmetricFunction, SymmetricFunctionAlgebra_generic.Element))
  or not g for g in args):
  raise ValueError("all arguments must be (possibly lazy) symmetric functions")
 
@@ -7200,9 +7199,8 @@ def arithmetic_product(self, *args):
  """
  if len(args) != self.parent()._arity:
  raise ValueError("arity must be equal to the number of arguments provided")
- from sage.combinat.sf.sfa import is_SymmetricFunction
- if not all(isinstance(g, LazySymmetricFunction)
- or is_SymmetricFunction(g)
+ from sage.combinat.sf.sfa import SymmetricFunctionAlgebra_generic
+ if not all(isinstance(g, (LazySymmetricFunction, SymmetricFunctionAlgebra_generic.Element))
  or not g for g in args):
  raise ValueError("all arguments must be (possibly lazy) symmetric functions")