Quick Questions

[Michael Witten]

Is it possible to implement 'break' and 'continue' in Io?

Should 'break' and 'continue' be considered operators?

Should 'return' be referred to as a "method"?
("Any part of a block can return immediately using the return method")

Is it necessary to give 'return' special syntax?

How can one create user-defined operators?
["User defined operators (that don't have a standard operator name) are
   performed left to right."]

It's not immediately obvious how special 'keywords' and operators are
handled. For instance:

        Io> and := 1
        ==> 1
        Io> 1 + and
        ==> 2
        Io> and + 1
        ==> 1
        Io> and + 100
        ==> 1
        Io> and + and
        ==> 1

Also:

        Io> and := false
        ==> false
        Io> and or 1
        ==> false

Also:

        Io> return := 1
        ==> 1
        Io> 1 + return
        ==> 2
        Io> return + 1
        ==> 1

strange, but consistent:
(I imagine IDs/addresses are being compared;
  'true' must be created before 'false', an
  unsafe assumption some programmer could use):

        Io> true < false
        ==> true
        Io> false < true
        ==> false
        Io> true > false
        ==> false
        Io> false > true
        ==> true

Also, there is more special treatment:

        Io> false := true
        ==> true
        Io> false
        ==> false

Shouldn't 'true' and 'false' be slots of Lobby?

Thanks for your help,
Michael Witten

[Jeremy Tregunna]

It is, see the stopStatus stuff.

--
Jeremy Tregunna
jtregunna@...



On 10-Jun-08, at 2:32 AM, Michael Witten wrote:

> Is it possible to implement 'break' and 'continue' in Io?
>
> Should 'break' and 'continue' be considered operators?
>
> Should 'return' be referred to as a "method"?
> ("Any part of a block can return immediately using the return method")
>
> Is it necessary to give 'return' special syntax?
>
> How can one create user-defined operators?
> ["User defined operators (that don't have a standard operator name)  
> are
>   performed left to right."]
>
> It's not immediately obvious how special 'keywords' and operators are
> handled. For instance:
>
> Io> and := 1
> ==> 1
> Io> 1 + and
> ==> 2
> Io> and + 1
> ==> 1
> Io> and + 100
> ==> 1
> Io> and + and
> ==> 1
>
> Also:
>
> Io> and := false
> ==> false
> Io> and or 1
> ==> false
>
> Also:
>
> Io> return := 1
> ==> 1
> Io> 1 + return
> ==> 2
> Io> return + 1
> ==> 1
>
> strange, but consistent:
> (I imagine IDs/addresses are being compared;
>  'true' must be created before 'false', an
>  unsafe assumption some programmer could use):
>
> Io> true < false
> ==> true
> Io> false < true
> ==> false
> Io> true > false
> ==> false
> Io> false > true
> ==> true
>
> Also, there is more special treatment:
>
> Io> false := true
> ==> true
> Io> false
> ==> false
>
> Shouldn't 'true' and 'false' be slots of Lobby?
>
> Thanks for your help,
> Michael Witten
>
> ------------------------------------
>
> Yahoo! Groups Links
>
>
>

[Michael Witten]

> On 10-Jun-08, at 2:32 AM, Michael Witten wrote:
>
>> Is it possible to implement 'break' and 'continue' in Io?
>>
>> Should 'break' and 'continue' be considered operators?
>>
>> Should 'return' be referred to as a "method"?
>> ("Any part of a block can return immediately using the return  
>> method")
>>
>> Is it necessary to give 'return' special syntax?
>>
>> How can one create user-defined operators?
>> ["User defined operators (that don't have a standard operator name)
>> are
>>  performed left to right."]
>>
>> It's not immediately obvious how special 'keywords' and operators are
>> handled. For instance:
>>
>> Io> and := 1
>> ==> 1
>> Io> 1 + and
>> ==> 2
>> Io> and + 1
>> ==> 1
>> Io> and + 100
>> ==> 1
>> Io> and + and
>> ==> 1
>>
>> Also:
>>
>> Io> and := false
>> ==> false
>> Io> and or 1
>> ==> false
>>
>> Also:
>>
>> Io> return := 1
>> ==> 1
>> Io> 1 + return
>> ==> 2
>> Io> return + 1
>> ==> 1
>>
>> strange, but consistent:
>> (I imagine IDs/addresses are being compared;
>> 'true' must be created before 'false', an
>> unsafe assumption some programmer could use):
>>
>> Io> true < false
>> ==> true
>> Io> false < true
>> ==> false
>> Io> true > false
>> ==> false
>> Io> false > true
>> ==> true
>>
>> Also, there is more special treatment:
>>
>> Io> false := true
>> ==> true
>> Io> false
>> ==> false
>>
>> Shouldn't 'true' and 'false' be slots of Lobby?
>>
>> Thanks for your help,
>> Michael Witten
>

> On 10 Jun 2008, at 5:25 AM, Jeremy Tregunna wrote:
> It is, see the stopStatus stuff.


I had a few more questions.

Sincerely,
Michael Witten

[Gavin Kistner]

On 10-Jun-08, at 2:32 AM, Michael Witten wrote:
> Is it possible to implement 'break' and 'continue' in Io?
>
> Should 'break' and 'continue' be considered operators?
>
> Should 'return' be referred to as a "method"?
> ("Any part of a block can return immediately using the return
> method")
>
> Is it necessary to give 'return' special syntax?

According to the below, 'break' and 'continue' are not operators, but  
'return' is. (Presumably it's treated as a binary operator whose  
implementation simply ignores the left operand.)

Io 20080120
Io> OperatorTable
==> OperatorTable_0x348360:
Operators
   0   ? @ @@
   1   **
   2   % * /
   3   + -
   4   << >>
   5   < <= > >=
   6   != ==
   7   &
   8   ^
   9   |
   10  && and
   11  or ||
   12  ..
   13  %= &= *= += -= /= <<= >>= ^= |=
   14  return

Assign Operators
   ::= newSlot
   :=  setSlot
   =   updateSlot

To add a new operator: OperatorTable addOperator("+", 4) and implement  
the + message.
To add a new assign operator: OperatorTable addAssignOperator("=",  
"updateSlot") and implement the updateSlot message.