[sipify] Replace nullptr with None in docstrings

Since nullptr has no meaning to Python devs

python/core/qgspropertytransformer.sip

@@ -261,7 +261,7 @@ class QgsPropertyTransformer
  \param fieldName will be set to a field name which is used to calculate the input
  to the property transformer. This will be set to an
  empty string if an expression is the transformer input.
- \returns corresponding property transformer, or nullptr if expression could not
+ \returns corresponding property transformer, or None if expression could not
  be parsed to a transformer.
 %End
 
@@ -323,7 +323,7 @@ class QgsGenericNumericTransformer : QgsPropertyTransformer
  \param fieldName will be set to a field name which is used to calculate the input
  to the property transformer. This will be set to an
  empty string if an expression is the transformer input.
- \returns corresponding QgsSizeScaleTransformer, or nullptr if expression could not
+ \returns corresponding QgsSizeScaleTransformer, or None if expression could not
  be parsed to a size scale transformer.
 %End
 
@@ -449,7 +449,7 @@ class QgsSizeScaleTransformer : QgsPropertyTransformer
  \param fieldName will be set to a field name which is used to calculate the input
  to the property transformer. This will be set to an
  empty string if an expression is the transformer input.
- \returns corresponding QgsSizeScaleTransformer, or nullptr if expression could not
+ \returns corresponding QgsSizeScaleTransformer, or None if expression could not
  be parsed to a size scale transformer.
 %End
 

python/core/raster/qgsrasterfilewriter.sip

@@ -48,7 +48,7 @@ class QgsRasterFileWriter
 .. note::
 
    Does not work with tiled mode enabled.
- \returns Instance of data provider in editing mode (on success) or null on error.
+ \returns Instance of data provider in editing mode (on success) or None on error.
 .. versionadded:: 3.0
 %End
 

scripts/sipify.pl

@@ -14,6 +14,9 @@ sub processDoxygenLine
     $line =~ s/\\a //g;
     # replace :: with . (changes c++ style namespace/class directives to Python style)
     $line =~ s/::/./g;
+	# replace nullptr with None (nullptr means nothing to Python devs)
+	$line =~ s/\bnullptr\b/None/g;
+
     if ( $line =~ m/[\\@](ingroup|class)/ ) {
         return ""
     }

src/core/raster/qgsrasterfilewriter.h

@@ -59,7 +59,7 @@ class CORE_EXPORT QgsRasterFileWriter
      * Returned provider may be used to initialize the raster using writeBlock() calls.
      * Ownership of the returned provider is passed to the caller.
      * \note Does not work with tiled mode enabled.
-     * \returns Instance of data provider in editing mode (on success) or null on error.
+     * \returns Instance of data provider in editing mode (on success) or nullptr on error.
      * \since QGIS 3.0
      */
     QgsRasterDataProvider *createOneBandRaster( Qgis::DataType dataType,

tests/scripts/sipifyheader.expected.sip

@@ -131,6 +131,11 @@ Factory annotation
  Here's some comment mentioning another class QgsAutoAwesomemater.makeLessAwesome.
 %End
 
+    MyPointer *pointerReturnValue();
+%Docstring
+ I return a pointer. If something bad happens, I return None.
+%End
+
     bool isOKwithErrMesg( QString &ErrMsg /Out/ );
 
     void InOutParam( bool &ok = true /In,Out/ );

tests/scripts/sipifyheader.h

@@ -163,6 +163,11 @@ class CORE_EXPORT QgsSipifyHeader : public QtClass<QVariant>, private Ui::QgsBas
      */
     void LongDocStringMethodWithBrief();
 
+    /**
+     * I return a pointer. If something bad happens, I return nullptr.
+     */
+    MyPointer *pointerReturnValue();
+
     bool isOKwithErrMesg( QString &ErrMsg SIP_OUT );
 
     void InOutParam( bool &ok = true SIP_INOUT );