From: Dave Howell <groups@...>
Date: 2006-01-05T07:47:28+09:00
Subject: Re: On Symbols


On Jan 4, 2006, at 14:06, Dave Howell wrote:

>
> On Dec 30, 2005, at 5:39, Devin Mullins wrote:
>
>> Hey, all you lurkers:
>>
>> Have any of the explanations in the thread (What is the difference 
>> between :foo and "foo" ?) helped you understand symbols?

Gregory Brown's examples showing object IDs have provided some hints, 
although I now feel an awful lot like Alice:

	'You are sad,' the Knight said in an anxious tone: 'let me sing you a 
song to comfort you.'
	'Is it very long?' Alice asked, for she had heard a good deal of 
poetry that day.
	'It's long,' said the Knight, 'but very, VERY beautiful. Everybody 
that hears me sing it--either it brings the TEARS into their eyes, or 
else--'
	'Or else what?' said Alice, for the Knight had made a sudden pause.
	'Or else it doesn't, you know. The name of the song is called 
"HADDOCKS' EYES."'
	'Oh, that's the name of the song, is it?' Alice said, trying to feel 
interested.
	'No, you don't understand,' the Knight said, looking a little vexed. 
'That's what the name is CALLED. The name really IS "THE AGED AGED 
MAN."'
	'Then I ought to have said "That's what the SONG is called"?' Alice 
corrected herself.
	'No, you oughtn't: that's quite another thing! The SONG is called 
"WAYS AND MEANS": but that's only what it's CALLED, you know!'
	'Well, what IS the song, then?' said Alice, who was by this time 
completely bewildered.
	'I was coming to that,' the Knight said. So saying, he stopped his 
horse and let the reins fall on its neck: then, slowly beating time 
with one hand, and with a faint smile lighting up his gentle foolish 
face, as if he enjoyed the music of his song, he began.


I'm developing the very strong suspicion that no explanation of symbols 
will get far unless it's part of a broader context that includes 
variables and references.

dblack said:
> a = "string" # a contains a reference to that string
and Gregory provided examples that indicate something more complicated: 
the `a' above contains a reference to an object, created especially for 
that variable, that contains six characters. Doing it again with 
variable `b' gives you an identical twin.

>  a = 1        # a contains the actual (immediate) value 1

Except the example would seem to contradict this statement. `a' `b' and 
`c' do not contain actual anythings. They contain references to the 
same object, that object which is the value "1".

Maybe. I guess it depends on what, exactly, the .object_id method 
returns, or on what "actual" or "immediate" means. It would appear it 
means something much less immediate than I'd expect.

"Named number" is beginning to make sense, to the degree that it's now 
clear there's some kind of serious difference between strings and (some 
kinds of?) numbers in Ruby.

On the other hand, there's still some serious ambiguity, because 
Gregory's numbers and strings were put into variables, but the symbols 
weren't stored in variables. What I need to figure out is how does a 
symbol differ from a string literal, numeric literal, or variable, not 
how it differs from a string or number IN a variable.

Onward.....

Once again, a gentle reminder: please feel free to comment on the 
learning process I'm documenting if you like, but do NOT respond if 
you're going to try to explain more about symbols and whatnot. Thanks!