Ticket #5970: weakref_poly_ring.patch

sage/rings/polynomial/polynomial_ring_constructor.py

@@ -355 +355 @@
 def _get_from_cache(key):
     try:
         if _cache.has_key(key):
-            return _cache[key] #()
+            r =  _cache[key]
+            if isinstance(r,weakref.ReferenceType):
+                return r()
+            else:
+                return r
     except TypeError, msg:
-        raise TypeError, 'key = %s\n%s'%(key,msg)        
+        raise TypeError, 'key = %s\n%s'%(key,msg)
     return None
 
-def _save_in_cache(key, R):
+def _save_in_cache(key, R, weak=False):
     try:
-        #_cache[key] = weakref.ref(R)
-         _cache[key] = R
+        if weak:
+            _cache[key] = weakref.ref(R)
+        else:
+            _cache[key] = R
     except TypeError, msg:
         raise TypeError, 'key = %s\n%s'%(key,msg)
 
@@ -410 +416 @@
     if hasattr(R, '_implementation_names'):
         for name in R._implementation_names:
             real_key = key[0:3] + (name,)
-            _save_in_cache(real_key, R)
+            _save_in_cache(real_key, R, weak=False)
     else:
-        _save_in_cache(key, R)
+        _save_in_cache(key, R,  weak=False)
     return R
 
 def _multi_variate(base_ring, names, n, sparse, order):
@@ -429 +435 @@
         return R
 
     from sage.rings.polynomial.multi_polynomial_libsingular import MPolynomialRing_libsingular
+
     if m.integral_domain.is_IntegralDomain(base_ring):
         if n < 1:
             R = m.MPolynomialRing_polydict_domain(base_ring, n, names, order)
@@ -443 +450 @@
         except ( TypeError, NotImplementedError ):
             R = m.MPolynomialRing_polydict(base_ring, n, names, order)
 
-    _save_in_cache(key, R)
+    _save_in_cache(key, R, weak=True)
     return R
 
 def BooleanPolynomialRing_constructor(n=None, names=None, order="lex"):
@@ -520 +527 @@
     from sage.rings.polynomial.pbori import BooleanPolynomialRing
     R = BooleanPolynomialRing(n, names, order)
 
-    _save_in_cache(key, R)
+    _save_in_cache(key, R, weak=True)
     return R