#167 enable Exceptions GDAL OGR Py bindings plus text chanegs (#171)

Author: justb4

workshop/jupyter/content/notebooks/04-vector-data.ipynb

@@ -479,8 +479,8 @@
    "cell_type": "markdown",
    "metadata": {},
    "source": [
-    "### Buffer\n",
-    "First we need to open the *Data Source*, printing the number of Layers."
+    "### Basic programming patterns\n",
+    "First, we open a *Data Source* and print its number of *Layers*. Note that we also globally enable GDAL Exceptions. By default, the GDAL/OGR Python bindings do not raise exceptions when errors occur. Instead, they return an error value such as `None` and write an error message to `sys.stdout`. You can enable exceptions by calling the `UseExceptions()` function. This is a recommended practice. See [this tutorial](https://pcjericks.github.io/py-gdalogr-cookbook/gdal_general.html#enable-python-exceptions)."
    ]
   },
   {
@@ -493,7 +493,11 @@
    },
    "outputs": [],
    "source": [
-    "from osgeo import ogr\n",
+    "from osgeo import ogr, gdal\n",
+    "\n",
+    "# Exceptions will get raised on anything >= gdal.CE_Failure\n",
+    "gdal.UseExceptions()\n",
+    "\n",
     "ds = ogr.Open('../data/countries.gpkg')\n",
     "print(ds)\n",
     "print(ds.GetLayerCount())"
@@ -502,10 +506,7 @@
   {
    "cell_type": "markdown",
    "metadata": {},
-   "source": [
-    "Next we have to fetch and open the *Layer*. NB for files, there is usually just one layer, index `0`, \n",
-    "within the Data Source (DS), but for example for a database DS, a Layer is refers to a concrete table)."
-   ]
+   "source": "Next we fetch and open a *Layer*. NB for files like GeoJSON, there is usually just one layer, at index 0, within the Data Source (DS). Datasources like GeoPackages and databases in general may have multiple Layers, where a Layer refers to a concrete table."
   },
   {
    "cell_type": "code",
@@ -525,9 +526,7 @@
   {
    "cell_type": "markdown",
    "metadata": {},
-   "source": [
-    "Show the schema of the layer and the definition of its geometry type:"
-   ]
+   "source": "Show the schema of the Layer and the definition of its geometry type:"
   },
   {
    "cell_type": "code",
@@ -1772,7 +1771,7 @@
    "name": "python",
    "nbconvert_exporter": "python",
    "pygments_lexer": "ipython3",
-   "version": "3.11.4"
+   "version": "3.10.12"
   },
   "vscode": {
    "interpreter": {
@@ -1781,5 +1780,5 @@
   }
  },
  "nbformat": 4,
- "nbformat_minor": 2
+ "nbformat_minor": 4
 }