Added a convenience method to RBA::Layout for creating a temp layer

src/db/gsiDeclDbLayout.cc

@@ -371,6 +371,11 @@ static unsigned int get_layer (db::Layout *l, const db::LayerProperties &lp)
   }
 }
 
+static unsigned int get_layer0 (db::Layout *l)
+{
+  return get_layer (l, db::LayerProperties ());
+}
+
 static unsigned int get_layer1 (db::Layout *l, const std::string &name)
 {
   return get_layer (l, db::LayerProperties (name));
@@ -1268,6 +1273,15 @@ Class<db::Layout> decl_Layout ("Layout",
     "You can convert coordinates to micrometers by multiplying the integer value with the database unit.\n"
     "Typical values for the database unit are 0.001 micrometer (one nanometer).\n"
   ) +
+  gsi::method_ext ("layer", &get_layer0,
+    "@brief Finds or creates a new internal layer\n"
+    "\n"
+    "This method will create a new internal layer and return the layer index for this layer.\n"
+    "The layer does not have any properties attached to it. That means, it is not going to be saved "
+    "to a layout file unless it is given database properties with \\set_info.\n"
+    "\n"
+    "This method has been introduced in version 0.25.\n"
+  ) +
   gsi::method_ext ("layer", &get_layer,
     "@brief Finds or creates a layer with the given properties\n"
     "@args info\n"

testdata/ruby/dbLayout.rb

@@ -162,12 +162,17 @@ class DBLayout_TestClass < TestBase
     b = ly.layer(RBA::LayerInfo.new(3, 0))
     assert_equal(a, b)
     assert_equal(ll(ly), "3/0")
-    b = ly.layer(RBA::LayerInfo.new)
+    bb = b
+    b = ly.layer
     assert_equal(ll(ly), "3/0,")
+    assert_equal(b != bb, true)
+    bb = b
     b = ly.layer(RBA::LayerInfo.new)
     assert_equal(ll(ly), "3/0,,")
+    assert_equal(b != bb, true)
     n = ly.layer(RBA::LayerInfo.new ("hallo"));
     assert_equal(ll(ly), "3/0,,,hallo")
+    assert_equal(b != n, true)
 
     ly = RBA::Layout.new
     li = ly.layer(2, 0)