editing - Getting number of new features to be stored in layers using PyQGIS?

In PyQGIS, how can I get the number of features that have been created in a given layer and that are pending to be saved in the layer when "Toggle editing" or "Saving layer edits"?

Answer

Say that you have a vector layer referenced:

lyr = iface.activeLayer()

At this point, I assume you start an edit session and digitize some features.

Now you can use the QgsVectorLayerEditBuffer class, in this way:

if lyr.editBuffer():

    print len( lyr.editBuffer().addedFeatures() ), "features to add!"

addedFeatures gives you a dictionary of new features that are pending. As you're interested in the count, you can use len().