[docs] Drop pl.metrics and define classes with explicit superclass (#231)

* Update docs

* Fix doctest

* Add docs/source/generated/ to gitignore

.gitignore

@@ -57,6 +57,7 @@ coverage.xml
 # Sphinx documentation
 docs/_build/
 docs/source/api/
+docs/source/generated/
 docs/source/*.md
 
 # PyBuilder

docs/source/pages/lightning.rst

@@ -19,23 +19,25 @@ While TorchMetrics was built to be used with native PyTorch, using TorchMetrics
 
 The example below shows how to use a metric in your `LightningModule <https://pytorch-lightning.readthedocs.io/en/stable/common/lightning_module.html>`_:
 
-.. code-block:: python
+.. testcode:: python
 
-    def __init__(self):
-        ...
-        self.accuracy = pl.metrics.Accuracy()
+    class MyModel(LightningModule):
 
-    def training_step(self, batch, batch_idx):
-        x, y = batch
-        preds = self(x)
-        ...
-        # log step metric
-        self.log('train_acc_step', self.accuracy(preds, y))
-        ...
+        def __init__(self):
+            ...
+            self.accuracy = torchmetrics.Accuracy()
 
-    def training_epoch_end(self, outs):
-        # log epoch metric
-        self.log('train_acc_epoch', self.accuracy.compute())
+        def training_step(self, batch, batch_idx):
+            x, y = batch
+            preds = self(x)
+            ...
+            # log step metric
+            self.log('train_acc_step', self.accuracy(preds, y))
+            ...
+
+        def training_epoch_end(self, outs):
+            # log epoch metric
+            self.log('train_acc_epoch', self.accuracy.compute())
 
 ********************
 Logging TorchMetrics
@@ -56,25 +58,27 @@ If ``on_epoch`` is True, the logger automatically logs the end of epoch metric v
     or reduction functions.
 
 
-.. code-block:: python
+.. testcode:: python
 
-    def __init__(self):
-        ...
-        self.train_acc = pl.metrics.Accuracy()
-        self.valid_acc = pl.metrics.Accuracy()
+    class MyModule(LightningModule):
 
-    def training_step(self, batch, batch_idx):
-        x, y = batch
-        preds = self(x)
-        ...
-        self.train_acc(preds, y)
-        self.log('train_acc', self.train_acc, on_step=True, on_epoch=False)
+        def __init__(self):
+            ...
+            self.train_acc = torchmetrics.Accuracy()
+            self.valid_acc = torchmetrics.Accuracy()
 
-    def validation_step(self, batch, batch_idx):
-        logits = self(x)
-        ...
-        self.valid_acc(logits, y)
-        self.log('valid_acc', self.valid_acc, on_step=True, on_epoch=True)
+        def training_step(self, batch, batch_idx):
+            x, y = batch
+            preds = self(x)
+            ...
+            self.train_acc(preds, y)
+            self.log('train_acc', self.train_acc, on_step=True, on_epoch=False)
+
+        def validation_step(self, batch, batch_idx):
+            logits = self(x)
+            ...
+            self.valid_acc(logits, y)
+            self.log('valid_acc', self.valid_acc, on_step=True, on_epoch=True)
 
 .. note::
 
@@ -85,15 +89,17 @@ If ``on_epoch`` is True, the logger automatically logs the end of epoch metric v
 
     .. testcode:: python
 
-        def training_step(self, batch, batch_idx):
-            data, target = batch
-            preds = self(data)
-            # ...
-            return {'loss' : loss, 'preds' : preds, 'target' : target}
+        class MyModule(LightningModule):
 
-        def training_step_end(self, outputs):
-            #update and log
-            self.metric(outputs['preds'], outputs['target'])
-            self.log('metric', self.metric)
+            def training_step(self, batch, batch_idx):
+                data, target = batch
+                preds = self(data)
+                # ...
+                return {'loss' : loss, 'preds' : preds, 'target' : target}
+
+            def training_step_end(self, outputs):
+                #update and log
+                self.metric(outputs['preds'], outputs['target'])
+                self.log('metric', self.metric)
 
 For more details see `Lightning Docs <https://pytorch-lightning.readthedocs.io/en/stable/extensions/logging.html#logging-from-a-lightningmodule>`_

docs/source/pages/overview.rst

@@ -1,3 +1,7 @@
+.. testsetup:: *
+
+    import torch
+    from pytorch_lightning.core.lightning import LightningModule
 
 ########
 Overview
@@ -91,7 +95,7 @@ the native `MetricCollection`_ module can also be used to wrap multiple metrics.
 
     from torchmetrics import Accuracy, MetricCollection
 
-    class MyModule():
+    class MyModule(torch.nn.Module):
         def __init__(self):
             ...
             # valid ways metrics will be identified as child modules
@@ -238,7 +242,7 @@ inside your LightningModule
 
     from torchmetrics import Accuracy, MetricCollection, Precision, Recall
 
-    class MyModule():
+    class MyModule(LightningModule):
         def __init__(self):
             metrics = MetricCollection([Accuracy(), Precision(), Recall()])
             self.train_metrics = metrics.clone(prefix='train_')