Function Implementation in Header Files

[atishelmanch]

Is there a reason that for many classes, both the header and cc files are used to define and implement functions? If not, it would probably make more sense to define the functions in the header files and implement them in the cc files.

For example, the EcalFenixStrip class [.h] [.cc]

[.h] https://github.com/CMS-ECAL-Trigger-Group/SimCalorimetry/blob/Odd-Weights-Filter-Dev/EcalTrigPrimAlgos/interface/EcalFenixStrip.h
[.cc] https://github.com/CMS-ECAL-Trigger-Group/SimCalorimetry/blob/Odd-Weights-Filter-Dev/EcalTrigPrimAlgos/src/EcalFenixStrip.cc

Also, for the EcalTrigPrimFunctionAlgo class, it almost appears that the roles of the header and cc files are swapped. Is there a reason for this?