Hello, I am new to smalltalk and I would really appreciate your help so I can better use and understand Pharo. So here is the problem, I wanted to implement a function to get the value of my tree struct nodes in a recursive manner and I wanted to concatenate them to a String ( aText ) and later show them on the Transcript. showLists | aText | aText := lol level, (String with: Character cr). self recursiveShowLists: lol withText: aText tabsNumber: 1. recursiveShowLists: aLoL withText: aText tabsNumber: aNumb | counter index | aLoL lols isEmpty ifFalse: [ counter := 1. [ counter <= aNumb ] whileTrue: [ aText := aText , (String with: Character tab). counter := counter + 1 ]. index := 1. aNumb := aNumb + 1. LoL lols do: [ :each | aText := aText , each level , (String with: Character cr) ]. ] Without having the last line ( LoL lols do: ... ) everything works fine but when I include it and as soon as debugger reaches to [counter <= aNumb ] and wants to evaluate it, my arguments start to act weird. aText will become nil and aNumb will hold te value of aText! I fixed this issue by adding another temporary variable ( copyText ) and instead of direct assignment of aText I used the copyText: recursiveShowLists: aLoL withText: aText tabsNumber: aNumb | counter index copyText | copyText := aText. aLoL lols isEmpty ifFalse: [ counter := 1. [ counter <= aNumb ] whileTrue: [ copyText := copyText , (String with: Character tab). counter := counter + 1 ]. index := 1. aLoL lols do: [ :each | copyText := copyText , each level , (String with: Character cr) ] ] I really like to know the reason behind this issue, I appreciate all the explanations. Thanks, Aria -- View this message in context: http://forum.world.st/I-need-some-explaination-about-arguements-assignment-t... Sent from the Pharo Smalltalk Users mailing list archive at Nabble.com.