Get a data product from the event (GenParticleCollection) and print out the size of the data product (number of generted tracks).
# Hard code the module label of the creator module.
Handles can be used as pointers. See Ex03Activity01_module.cc and ex03Activity01.fcl.
# ex03Activity02.fcl this runs the event dumper. Look at the names of the products in the event. Notice run scope data products.
# Remove the const. Observe the error message
# Misspell the name of the module that created the data product. Observe the error message.
# Rewrite the exercise to use the handle as a pointer.
# In the source area, art-workbook/artwb, do: diff Ex01/CMakeLists.txt Ex03/CMakeLists.txt Note that one line has been added, the name of the library that contains the data products.
Ideas to discuss
What is a data product
# Find source for GenparticleCollection.h and GenParticle.h.
# GenParticleCollection is a typedef. Under the covers it is just a std::vector<GenParticle>. Explain why we used a typedef.
# const correctness in product access.
# Explain about the overhead everytime that you dereference a handle. Use judgement about when to use which style of access.
# Explain the naming scheme of data products - forward reference for the instance name part.