Robert Dailey wrote: > First, take a look at my example code: > ----------------------------------------------------- > import csv > > def pass1( reader ): > print reader.next() > print reader.next() > > def pass2( reader ): > print reader.next() > print reader.next() > > reader = csv.reader( open( "C:/IT/Method/SpaceImpact/code/tools/ > ProfileViewer/performance_profile.csv", "rb" ) ) > > pass1( reader ) > pass2( reader ) > ----------------------------------------------------- > > The output is as follows: > ----------------------------------------------------- > ['0', 'root', '00:01:32.793591', '1'] > ['1', 'Engine::Tick', '00:00:25.886411', '1851'] > ['2', 'Sprite::Tick', '00:00:00.001495', '385'] > ['2', 'Entity::Tick', '00:00:00.001485', '45'] > ----------------------------------------------------- > > I expected the output to be this: > ----------------------------------------------------- > ['0', 'root', '00:01:32.793591', '1'] > ['1', 'Engine::Tick', '00:00:25.886411', '1851'] > ['0', 'root', '00:01:32.793591', '1'] > ['1', 'Engine::Tick', '00:00:25.886411', '1851'] > ----------------------------------------------------- > > My understanding is that objects are passed by reference, meaning > there is no hard copy of the data, however the copies passed to > functions do not affect the version passed in. In other words, when I > call "next" on the reference passed into each function, it should not > affect the variable that was originally passed in. > > I'm attempting to use recursion to build a TreeCtrl in wxPython using > this data, and I can't get it to work properly if the variable outside > of the function call ends up having its state (e.g., its "next" > pointer) modified by passing it into other functions. > > Any tips on getting this to work? I'm a native C++ programmer still > learning Python, so I apologize for any confusion. Thanks. >
By reference means that mutable objects can be modified (in place) by the functions that they are passed into. This is a common mistake people make when they first get started. Normally lists seem to throw people first. I don't know how long the file is, but you probably should just read the entire file into memory and process it from there. -Larry -- http://mail.python.org/mailman/listinfo/python-list
