如何在Smalltalk中循环“继续”

Question

I have following code where I want to 'continue' if i is less than 5:

1 to: 10 do: [ :i |
    i < 5 ifTrue: [ continue ].
    'Square of i = ', (i * i) printNl.
]

'continue' in above code is obviously not working. I know that exit can be used to break out of a loop. But how to continue ? Thanks for your help.

Answer 1

In your case you can simply use ifFalse: :

1 to: 10 do: [ :i |
    i < 5 ifTrue: [ 
        "Any code you need"
    ] ifFalse: [ 'Square of i = ', (i * i) printNl ].
]

The following code will probably work only in Pharo. (it will not work in GNU Smalltalk, in Smalltalk/X it could work if you use correct modulo. The % returns complex number):

    1 to: 10 do: [ :i |
        [ :continue |
            i % 5 = 0 ifTrue: [ 
                Transcript show: i; cr.
                continue value ].
            Transcript 
                show: i;
                show: ', '.     
        ] valueWithExit.
    ]

The valueWithExit the implementation in Pharo:

valueWithExit 
      self value: [ ^nil ]

The meaning:

The receiver must be block of one argument. When it is evaluated and is passed a block, when a value message is send will exit the receiver block (returning nil in Pharo).