kernel and parallel magics: allow kernel name to optional, use 'default'

jupyter_kernel/magics/kernel_magic.py

@@ -8,9 +8,9 @@
 class KernelMagic(Magic):
     kernels = {}
 
-    def line_kernel(self, module_name, class_name, kernel_name):
+    def line_kernel(self, module_name, class_name, kernel_name="default"):
         """
-        %kernel MODULE CLASS NAME - construct a kernel for sending code.
+        %kernel MODULE CLASS [NAME] - construct a kernel for sending code.
 
         Also returns the kernel as output.
 
@@ -28,9 +28,9 @@ def line_kernel(self, module_name, class_name, kernel_name):
         self.kernels[kernel_name] = class_()
         self.retval = self.kernels[kernel_name]
 
-    def cell_kernel(self, kernel_name):
+    def cell_kernel(self, kernel_name="default"):
         """
-        %%kernel NAME - send the cell code to the kernel.
+        %%kernel [NAME] - send the cell code to the kernel.
 
         Returns the result of the execution as output.
 
@@ -39,7 +39,7 @@ def cell_kernel(self, kernel_name):
             %%kernel bash
             ls -al 
 
-        Use `%kernel MODULE CLASS NAME` to create a kernel.
+        Use `%kernel MODULE CLASS [NAME]` to create a kernel.
         """
         self.retval = self.kernels[kernel_name].do_execute_direct(self.code)
         self.evaluate = False

jupyter_kernel/magics/parallel_magic.py

@@ -13,13 +13,13 @@ class ParallelMagic(Magic):
     kernel_name = None
     retval = None
 
-    def line_parallel(self, module_name, class_name, kernel_name, ids=None):
+    def line_parallel(self, module_name, class_name, kernel_name="default", ids=None):
         """
         %parallel MODULE CLASS NAME ids[...] - construct an interface to the cluster.
 
         Example:
 
-            %parallel bash_kernel BashKernel bash 
+            %parallel bash_kernel BashKernel 
             %parallel bash_kernel BashKernel bash [0, 2, 4]
 
         Use %px or %%px to send code to the cluster.
@@ -45,6 +45,7 @@ def line_parallel(self, module_name, class_name, kernel_name, ids=None):
        "class_name": class_name}, block=True)
         self.retval = None
 
+    ## px --kernel NAME
     def line_px(self, expression):
         """
         %px EXPRESSION - send EXPRESSION to the cluster.
@@ -59,6 +60,7 @@ def line_px(self, expression):
         """
         self.retval = self.view["kernel.do_execute_direct(\"%s\")" % expression.replace('"', '\\"')]
 
+    ## px --kernel NAME
     def cell_px(self):
         """
         %%px - send cell to the cluster.