Curves: remove _assure_has_components

Instead, just never access C.components directly, instead
use curve_components(C)

examples/AffinePlaneCurve.jl

@@ -165,13 +165,13 @@ end
 Return the reduced singular locus of `C` as a list whose first element is the affine plane curve consisting of the singular components of `C` (if any), and the second element is the list of the isolated singular points (which may be contained in the singular component). The singular component might not contain any point over the considered field.
 """
 function curve_singular_locus(C::AffinePlaneCurve)
-   _assure_has_components(C)
+   comp = curve_components(C)
    D = reduction(C)
    Pts = Array{Point, 1}()
    CC = Array{AffinePlaneCurve, 1}()
    # The components with multiplicity > 1 are singular
    f = []
-   for (h, c) in C.components
+   for (h, c) in comp
       if c != 1
          push!(f, h.eq)
       end

examples/PlaneCurve.jl

@@ -221,17 +221,6 @@ function Oscar.jacobi_ideal(C::PlaneCurve)
  return jacobi_ideal(C.eq)
 end
 
-################################################################################
-# Helping function
-
-function _assure_has_components(C::PlaneCurve)
-  if isempty(C.components)
-    T = typeof(C)
-    D = factor(C.eq)
-    C.components = Dict(T(x) => D.fac[x] for x in keys(D.fac))
-  end
-end
-
 ################################################################################
 # Components of the curve
 
@@ -241,7 +230,11 @@ end
 Return a dictionary containing the irreducible components of `C` and their multiplicity.
 """
 function curve_components(C::PlaneCurve)
-  _assure_has_components(C)
+  if isempty(C.components)
+    T = typeof(C)
+    D = factor(C.eq)
+    C.components = Dict(T(x) => D.fac[x] for x in keys(D.fac))
+  end
   return C.components
 end
 
@@ -255,8 +248,8 @@ end
 Return `true` if `C` is irreducible, and `false` otherwise.
 """
 function Oscar.isirreducible(C::PlaneCurve)
-  _assure_has_components(C)
-   return length(C.components) == 1 && all(isone, values(C.components))
+   comp = curve_components(C)
+   return length(comp) == 1 && all(isone, values(comp))
 end
 
 ################################################################################
@@ -300,10 +293,10 @@ function reduction(C::AffinePlaneCurve)
 end
 
 function reduction(C::ProjPlaneCurve)
-  _assure_has_components(C)
-  F = prod(D -> D.eq, keys(C.components))
+  comp = curve_components(C)
+  F = prod(D -> D.eq, keys(comp))
   rC = ProjPlaneCurve(F)
-  rC.components = Dict(ProjPlaneCurve(D.eq) => 1 for D in keys(C.components))
+  rC.components = Dict(ProjPlaneCurve(D.eq) => 1 for D in keys(comp))
   return rC
 end