On Mon, 15 Nov 2010 21:35:19 +0100
Simen kjaeraas simen.kja...@gmail.com wrote:
spir denis.s...@gmail.com wrote:
On Mon, 15 Nov 2010 12:44:24 -0500
bearophile bearophileh...@lycos.com wrote:
spir:
1. name objects automatically
I need some objects to know their name (as field on themselves). the
only solution I can else imagine is for the user write:
x = ...;
x.name = x;
What if you have two or more references to the same object?
I'm not sure what you mean. The said objects are patterns (instances of
a Pattern class hierachy). And indeed, they are multiply referenced
(that's precisely the point of writing a grammar ;-).
The two (or more) references could not be referred to by the same name.
Sure, they would point to the same object, but how could the object know
whether its functions were called from x or from y? While you may use the
same name everywhere for the same object, the x in function foo is a
different one from that in function bar, not to mention across modules.
Oh, yes! I see the point, now, thank you. But in the present case (and a few
others where I had to name objects), only the birth name is relevant. Here is
an example from written using the library I'm writing, I'm sure it's
self-explaining. I overloaded opCall in the top Pattern class so that it names
the object:
== test code
auto digits = new String(new Klass(0-9));
digits.name = digits;
auto DOT = new Literal(.);
DOT.name = DOT;
auto integer = new Compose(digits,DOT,digits);
integer.name = integer;
// output
writeln(digits.view());
writeln(integer.view());
writeln-);
integer.test(123.45);
writeln-);
integer.test(123.);
=== output ==
digits=[0-9]+
integer=(digits DOT digits)
-
pattern : integer=(digits DOT digits)
text : 123.45
outcome : (123 . 45)
-
Test Error: see outcome below.
-
pattern : integer=(digits DOT digits)
text : 123.
outcome : *failure*
-
*
End Of Text Error: end of text reached while matching
pattern digits=[0-9]+ at index 4
*
If I may come with a solution, it would be something like this:
mixin template New!( T, string name ) {
mixin( auto ~ name ~ = new T(\ ~ name ~ \));
}
Thank you again, I'll explore this path.
Denis
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