[Cuis] Left arrow and up arrow characters

[David Graham]

On 5/16/12 7:30 AM, Juan Vuletich wrote:
> David Graham wrote:
>> One of the first things that I noticed in Cuis, was that it uses left 
>> arrow for assignment and up arrows for return, just like what you see 
>> in the Blue Book(1).  I ran into a small problem with my "legacy" :) 
>> file naming standard ( underscores for separation ) and Juan helped 
>> me out with the following bit of advice:
>>
>> > Simply evaluating 'StrikeFont useUnderscore'displays the ASCII ^ and _
>> > glyphs. If you ever want to go back to left and up arrow, evaluate
>> > 'StrikeFont useLeftArrow'. I included both sets of glyphs so 
>> everybody can
>> > choose.
>>
>> > Please note that this doesn't affect the parser. In any case both _ 
>> and :=
>> > are valid for assignment, but not for use in selectors or variable 
>> names.
>> > Preferences #allowUnderscoreSelectors and 
>> #allowUnderscoreAssignments give
>> > you some control over this. If you set #allowUnderscoreSelectors to 
>> true
>> > and #allowUnderscoreAssignments to false, you get the standard 
>> behavior in
>> > many Smalltalks, where the underscore can be part of selectors or 
>> variable
>> > names. In this case, if you modify existing methods, you need to 
>> change
>> > assignments to be := so they will compile.
>>
>> I was little curious why the smalltalk creators picked those 
>> characters and discovered that the left arrow was used for assignment 
>> in Xerox's Mesa language, and in turn the Xerox Alto computer had a 
>> key with a left arrow.  Choosing these for smalltalk is obvious when 
>> you see the keyboard:
>>
>>
>> More pictures of the Alto can be found here (use the zoom feature to 
>> get a closeup of the keyboard):
>> http://www.computerhistory.org/revolution/input-output/14/347/1520?position=0 
>>
>>
>>
>>
>> (1) http://stephane.ducasse.free.fr/FreeBooks/BlueBook/
>
> The left and up arrows were part of the early 1963 ASCII standard. See 
> http://www.cs.tut.fi/~jkorpela/latin1/ascii-hist.html (scroll down to 
> half of page, CIRCUMFLEX ACCENT and LOW LINE). It was also in my first 
> computer, the Radio Shack Coco2: 
> http://en.wikipedia.org/wiki/File:Cocobvdg.png , and also on the 
> Commodore 64 and many other machines of that time.
>
> But yes, the main reason to keep those glyphs is to honor 
> Smalltalk-80. I also think that Smalltalk code looks better with them.
>
> Cheers,
> Juan Vuletich
Thanks for the addition, I didn't realize it was an ASCII standard.  I 
just wish my keyboard had the same placement as the alto (both are above 
the return key).

I vaguely remember those keys being on my C64, but that was a long time 
ago. :)