Revert "Revert "refactor: move xmodule folder to root""

xmodule/randomize_module.py

@@ -0,0 +1,125 @@
+# lint-amnesty, pylint: disable=missing-module-docstring
+
+import logging
+import random
+
+from django.utils.functional import cached_property
+from lxml import etree
+from web_fragments.fragment import Fragment
+from xblock.fields import Integer, Scope
+from xmodule.mako_module import MakoTemplateBlockBase
+from xmodule.seq_module import SequenceMixin
+from xmodule.xml_module import XmlMixin
+from xmodule.x_module import (
+    HTMLSnippet,
+    ResourceTemplates,
+    STUDENT_VIEW,
+    XModuleMixin,
+    XModuleToXBlockMixin,
+)
+
+log = logging.getLogger('edx.' + __name__)
+
+
+class RandomizeBlock(
+    SequenceMixin,
+    MakoTemplateBlockBase,
+    XmlMixin,
+    XModuleToXBlockMixin,
+    HTMLSnippet,
+    ResourceTemplates,
+    XModuleMixin,
+):
+    """
+    Chooses a random child xblock. Chooses the same one every time for each student.
+
+     Example:
+     <randomize>
+     <problem url_name="problem1" />
+     <problem url_name="problem2" />
+     <problem url_name="problem3" />
+     </randomize>
+
+    User notes:
+
+      - If you're randomizing amongst graded modules, each of them MUST be worth the same
+        number of points.  Otherwise, the earth will be overrun by monsters from the
+        deeps.  You have been warned.
+
+    Technical notes:
+      - There is more dark magic in this code than I'd like.  The whole varying-children +
+        grading interaction is a tangle between super and subclasses of descriptors and
+        modules.
+"""
+    choice = Integer(help="Which random child was chosen", scope=Scope.user_state)
+
+    resources_dir = None
+
+    filename_extension = "xml"
+
+    show_in_read_only_mode = True
+
+    @cached_property
+    def child(self):
+        """ Return XBlock instance of selected choice """
+        num_choices = len(self.get_children())
+
+        if self.choice is not None and self.choice > num_choices:
+            # Oops.  Children changed. Reset.
+            self.choice = None
+
+        if self.choice is None:
+            # choose one based on the system seed, or randomly if that's not available
+            if num_choices > 0:
+                if self.system.seed is not None:
+                    self.choice = self.system.seed % num_choices
+                else:
+                    self.choice = random.randrange(0, num_choices)
+
+        if self.choice is None:
+            return None
+        child = self.get_children()[self.choice]
+
+        if self.choice is not None:
+            log.debug("children of randomize module (should be only 1): %s", child)
+
+        return child
+
+    def get_child_descriptors(self):
+        """
+        For grading--return just the chosen child.
+        """
+        if self.child is None:
+            return []
+
+        return [self.child]
+
+    def student_view(self, context):
+        """
+        The student view.
+        """
+        if self.child is None:
+            # raise error instead?  In fact, could complain on descriptor load...
+            return Fragment(content="<div>Nothing to randomize between</div>")
+
+        return self.child.render(STUDENT_VIEW, context)
+
+    def get_html(self):
+        return self.studio_view(None).content
+
+    def get_icon_class(self):
+        return self.child.get_icon_class() if self.child else 'other'
+
+    def definition_to_xml(self, resource_fs):
+
+        xml_object = etree.Element('randomize')
+        for child in self.get_children():
+            self.runtime.add_block_as_child_node(child, xml_object)
+        return xml_object
+
+    def has_dynamic_children(self):
+        """
+        Grading needs to know that only one of the children is actually "real".  This
+        makes it use module.get_child_descriptors().
+        """
+        return True