Expose an extruderValues() function to value functions

It returns a list of values for all extruders so that things like max()
work.

Contributes to CURA-2009

cura/CuraApplication.py

@@ -28,6 +28,7 @@ from cura.SetParentOperation import SetParentOperation
 
 from UM.Settings.SettingDefinition import SettingDefinition, DefinitionPropertyType
 from UM.Settings.ContainerRegistry import ContainerRegistry
+from UM.Settings.SettingFunction import SettingFunction
 
 from UM.i18n import i18nCatalog
 
@@ -71,7 +72,6 @@ except ImportError:
     CuraVersion = "master"  # [CodeStyle: Reflecting imported value]
     CuraBuildType = ""
 
-
 class CuraApplication(QtApplication):
     class ResourceTypes:
         QmlFiles = Resources.UserType + 1
@@ -100,6 +100,7 @@ class CuraApplication(QtApplication):
         SettingDefinition.addSupportedProperty("global_inherits_stack", DefinitionPropertyType.Function, default = "-1")
         SettingDefinition.addSettingType("extruder", None, str, Validator)
 
+        SettingFunction.registerOperator("extruderValues", cura.Settings.ExtruderManager.getExtruderValues)
         ## Add the 4 types of profiles to storage.
         Resources.addStorageType(self.ResourceTypes.QualityInstanceContainer, "quality")
         Resources.addStorageType(self.ResourceTypes.VariantInstanceContainer, "variants")

cura/Settings/ExtruderManager.py

@@ -273,3 +273,25 @@ class ExtruderManager(QObject):
         global_stack = UM.Application.getInstance().getGlobalContainerStack()
         if global_stack and global_stack.getBottom():
             self.addMachineExtruders(global_stack.getBottom(), global_stack.getId())
+
+    @staticmethod
+    def getExtruderValues(name):
+        global_stack = UM.Application.getInstance().getGlobalContainerStack()
+
+        result = []
+        for extruder in ExtruderManager.getInstance().getMachineExtruders(global_stack.getId()):
+            value = extruder.getRawProperty(name, "value", use_next = False)
+
+            if not value:
+                continue
+
+            if isinstance(value, UM.Settings.SettingFunction):
+                value = value(extruder)
+
+            result.append(value)
+
+        if not result:
+            result.append(global_stack.getProperty(name, "value"))
+
+        return result
+