import ROOT,aa

"""
exmaple to show how to write an 'offline' file using OutputEventFile class.
"""


f = ROOT.OutputEventFile("myfile.root")

header = ROOT.Head()
header.set_line("sometag","custom_file")
f.write_header(header)


for i in range( 10 ) :
    
    evt = ROOT.Evt()

    evt.id = i
    evt.mc_trks.resize(1)
    evt.mc_trks[0].dir.set( 0,0,1 )
    evt.mc_trks[0].E = 1000

    f.write(evt)

del f # this closes the file

f = ROOT.EventFile( "myfile.root" )

for evt in f : 
    print(evt)