Smalltalk: adding new methods to existing classes


New methods added to the Integer class:
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mymax: x
    "returns the larger of x and receiver"

    x > self ifTrue: [^ x].
    ^ self


sumUpTo
    "returns the sum of the numbers from 1 up to the receiver"

    | sum |
    sum := 0.
    (1 to: self) do: [:x | sum := sum + x].
    ^ sum


sumUpToRec
    "returns the sum of the numbers from 1 up to the receiver, recursive version"
    "sample calls:"
    "5 sumUpToRec"
    "100 sumUpToRec"

    self <= 0 ifTrue: [^ 0].
    ^ self + ((self - 1) sumUpToRec)


myfactorial
    "returns the factorial of the receiver, recursive version"
    "sample call:"
    "7 myfactorial"

    self <= 0 ifTrue: [^ 1].
    ^ self * ((self - 1) myfactorial)


New method added to the Object class:
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print
    "show the receiver in the Transcript"

    Transcript show: self; cr.