Doc: Fixing several small issues (#6392)

The recursive workchain in code snippets can theoretically not run and 
is just confusing to have as an example for a user. It has been fixed by
using different name for the inner workchain.

In the classes `NodeCaching` and `ProcessNodeCaching` the
`is valid_cache` is a property. To not render it with method brackets,
the `:attr:` sphinx directive is used instead of `:meth:`.

docs/source/internals/engine.rst

@@ -20,14 +20,14 @@ There are several methods which the internal classes of AiiDA use to control the
 
 On the level of the generic :class:`orm.Node <aiida.orm.Node>` class:
 
-* The :meth:`~aiida.orm.nodes.caching.NodeCaching.is_valid_cache` property determines whether a particular node can be used as a cache.
+* The :attr:`~aiida.orm.nodes.caching.NodeCaching.is_valid_cache` property determines whether a particular node can be used as a cache.
   This is used for example to disable caching from failed calculations.
 * Node classes have a ``_cachable`` attribute, which can be set to ``False`` to completely switch off caching for nodes of that class.
   This avoids performing queries for the hash altogether.
 
 On the level of the :class:`Process <aiida.engine.processes.process.Process>` and :class:`orm.ProcessNode <aiida.orm.ProcessNode>` classes:
 
-* The :meth:`ProcessNodeCaching.is_valid_cache <aiida.orm.nodes.process.process.ProcessNodeCaching.is_valid_cache>` calls :meth:`Process.is_valid_cache <aiida.engine.processes.process.Process.is_valid_cache>`, passing the node itself.
+* The :attr:`ProcessNodeCaching.is_valid_cache <aiida.orm.nodes.process.process.ProcessNodeCaching.is_valid_cache>` calls :meth:`Process.is_valid_cache <aiida.engine.processes.process.Process.is_valid_cache>`, passing the node itself.
   This can be used in :class:`~aiida.engine.processes.process.Process` subclasses (e.g. in calculation plugins) to implement custom ways of invalidating the cache.
 * The :meth:`ProcessNodeCaching._hash_ignored_inputs <aiida.orm.nodes.process.process.ProcessNodeCaching._hash_ignored_inputs>` attribute lists the inputs that should be ignored when creating the hash.
   This is checked by the :meth:`ProcessNodeCaching.get_objects_to_hash <aiida.orm.nodes.process.process.ProcessNodeCaching.get_objects_to_hash>` method.

docs/source/topics/provenance/caching.rst

@@ -146,9 +146,9 @@ This method calls the iterator :meth:`~aiida.orm.nodes.caching.NodeCaching._iter
 To find the list of `source` nodes that are equivalent to the `target` that is being stored, :meth:`~aiida.orm.nodes.caching.NodeCaching._iter_all_same_nodes` performs the following steps:
 
 1. It queries the database for all nodes that have the same hash as the `target` node.
-2. From the result, only those nodes are returned where the property :meth:`~aiida.orm.nodes.caching.NodeCaching.is_valid_cache` returns ``True``.
+2. From the result, only those nodes are returned where the property :attr:`~aiida.orm.nodes.caching.NodeCaching.is_valid_cache` returns ``True``.
 
-The property :meth:`~aiida.orm.nodes.caching.NodeCaching.is_valid_cache` therefore allows to control whether a stored node can be used as a `source` in the caching mechanism.
+The property :attr:`~aiida.orm.nodes.caching.NodeCaching.is_valid_cache` therefore allows to control whether a stored node can be used as a `source` in the caching mechanism.
 By default, for all nodes, the property returns ``True``.
 However, this can be changed on a per-node basis, by setting it to ``False``
 
@@ -166,8 +166,8 @@ Setting the property to ``False``, will cause an extra to be stored on the node
 
 Through this method, it is possible to guarantee that individual nodes are never used as a `source` for caching.
 
-The :class:`~aiida.engine.processes.process.Process` class overrides the :meth:`~aiida.orm.nodes.caching.NodeCaching.is_valid_cache` property to give more fine-grained control on process nodes as caching sources.
-If either :meth:`~aiida.orm.nodes.caching.NodeCaching.is_valid_cache` of the base class or :meth:`~aiida.orm.nodes.process.process.ProcessNode.is_finished` returns ``False``, the process node is not a valid source.
+The :class:`~aiida.engine.processes.process.Process` class overrides the :attr:`~aiida.orm.nodes.caching.NodeCaching.is_valid_cache` property to give more fine-grained control on process nodes as caching sources.
+If either :attr:`~aiida.orm.nodes.caching.NodeCaching.is_valid_cache` of the base class or :meth:`~aiida.orm.nodes.process.process.ProcessNode.is_finished` returns ``False``, the process node is not a valid source.
 Likewise, if the process class cannot be loaded from the node, through the :meth:`~aiida.orm.nodes.process.process.ProcessNode.process_class`, the node is not a valid caching source.
 Finally, if the associated process class implements the :meth:`~aiida.engine.processes.process.Process.is_valid_cache` method, it is called, passing the node as an argument.
 If that returns ``True``, the node is considered to be a valid caching source.

docs/source/topics/workflows/include/snippets/workchains/run_workchain_submit_append.py

@@ -1,4 +1,7 @@
 from aiida.engine import WorkChain, append_
+from aiida.plugins.factories import CalculationFactory
+
+SomeOtherWorkChain = CalculationFactory('some.module')
 
 
 class SomeWorkChain(WorkChain):
@@ -12,7 +15,7 @@ def define(cls, spec):
 
     def submit_workchains(self):
         for i in range(3):
-            future = self.submit(SomeWorkChain)
+            future = self.submit(SomeOtherWorkChain)
             self.to_context(workchains=append_(future))
 
     def inspect_workchains(self):

docs/source/topics/workflows/include/snippets/workchains/run_workchain_submit_complete.py

@@ -1,4 +1,7 @@
 from aiida.engine import ToContext, WorkChain
+from aiida.plugins.factories import CalculationFactory
+
+SomeOtherWorkChain = CalculationFactory('some.module')
 
 
 class SomeWorkChain(WorkChain):
@@ -11,7 +14,7 @@ def define(cls, spec):
         )
 
     def submit_workchain(self):
-        future = self.submit(SomeWorkChain)
+        future = self.submit(SomeOtherWorkChain)
         return ToContext(workchain=future)
 
     def inspect_workchain(self):

docs/source/topics/workflows/include/snippets/workchains/run_workchain_submit_parallel.py

@@ -1,4 +1,7 @@
 from aiida.engine import WorkChain
+from aiida.plugins.factories import CalculationFactory
+
+SomeOtherWorkChain = CalculationFactory('some.module')
 
 
 class SomeWorkChain(WorkChain):
@@ -12,7 +15,7 @@ def define(cls, spec):
 
     def submit_workchains(self):
         for i in range(3):
-            future = self.submit(SomeWorkChain)
+            future = self.submit(SomeOtherWorkChain)
             key = f'workchain_{i}'
             self.to_context(**{key: future})
 

docs/source/topics/workflows/include/snippets/workchains/run_workchain_submit_parallel_nested.py

@@ -1,4 +1,7 @@
 from aiida.engine import WorkChain
+from aiida.plugins.factories import CalculationFactory
+
+SomeOtherWorkChain = CalculationFactory('some.module')
 
 
 class SomeWorkChain(WorkChain):
@@ -12,7 +15,7 @@ def define(cls, spec):
 
     def submit_workchains(self):
         for i in range(3):
-            future = self.submit(SomeWorkChain)
+            future = self.submit(SomeOtherWorkChain)
             key = f'workchains.sub{i}'
             self.to_context(**{key: future})