1st example reading external decay file for Py6, via pyupda

Configuration/Generator/python/Pythia_H0_pyupda_cfi.py

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+import FWCore.ParameterSet.Config as cms
+
+from Configuration.Generator.PythiaUESettings_cfi import *
+
+generator = cms.EDFilter("Pythia6GeneratorFilter",
+    pythiaHepMCVerbosity = cms.untracked.bool(True),
+    maxEventsToPrint = cms.untracked.int32(10),
+    # Print event
+    pythiaPylistVerbosity = cms.untracked.int32(3),
+    # Print decay tables
+#    pythiaPylistVerbosity = cms.untracked.int32(12),                         
+    filterEfficiency = cms.untracked.double(1.0),
+    comEnergy = cms.double(10000.0),
+#    crossSection = cms.untracked.double(55000000000.),
+    UseExternalGenerators = cms.untracked.bool(False),
+#
+    PythiaParameters = cms.PSet(
+        pythiaUESettingsBlock,
+        pythiaMyParameters = cms.vstring(
+# This is needed if you are introducing long-lived exotic particles.
+          'MSTJ(22)=1    ! Decay ALL unstable particles',
+
+          'MSEL=0',
+# Request gg -> H0 production
+          'MSUB(152)=1',
+          'MWID(35)=2 ! Let me set H0 properties'
+        ),
+#
+        PYUPDAParameters = cms.vstring(
+# Read my parameters
+         "PYUPDAFILE = 'Configuration/Generator/data/Pythia_H0_pyupda.in'"
+# Optionally call PYUPDA after PYINIT. This doesn't seem to be necessary.
+#         "PYUPDApostPYINIT"
+# Write current parameters
+#         "PYUPDAFILE = \'pyupda.out\'"
+#         "PYUPDAWRITE"
+        ),
+#
+        # This is a vector of ParameterSet names to be read, in this order
+        parameterSets = cms.vstring('pythiaUESettings', 
+                                    'pythiaMyParameters',
+                                    'PYUPDAParameters')
+    )
+)
+
+# this needs to get in somehow...
+#
+# genParticles.abortOnUnknownPDGCode = cms.untracked.bool(False)
+
+