It took me a while to recognize that string literals in REBOL don't
mean what they do in other languages. In another language (Perl, for
example) the statement
$a = "";
is translated into instructions that ask the interpreter to create a
new, empty string, then store a reference to that string in $a. By
contrast, a string literal in the source text is simply translated
into a reference to a string which is initialized with the literal's
value.
The result of translating the REBOL expression
b: [a: ""]
can be diagrammed as
b -> {{block! 1 *}}
|
V
<<a: *>>
|
V
{{string! 1 *}}
|
V
<<>>
Evaluating the expression
do b
modifies the state of affairs to
b -> {{block! 1 *}}
|
V
<<a: *>>
|
V
a -----------------> {{string! 1 *}}
|
V
<<>>
so that a now refers to the same string as b/2. Modifying the content
of that string has a side-effect visible to any reference to that
string.
>> b: [a: ""]
== [a: ""]
>> do b
== ""
>> append a "YOW!"
== "YOW!"
>> b
== [a: "YOW!"]
>> insert second b "HOO-"
== "YOW!"
>> a
== "HOO-YOW!"
>> b
== [a: "HOO-YOW!"]
So string literals in REBOL are just initilizers for anonymous strings.
-jn-
