From: "Florian Groß" <florgro@...>
Date: 2004-12-27T13:02:41+09:00
Subject: Allowing custom number literal suffixes?

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Moin!

On the ruby-muse mailing list which is a place for discussion of new 
ideas for Ruby there recently was a sub-thread concerning the 
introduction of user-defined number literal suffixes. These suffixes are 
already used in other languages and look like 1.5f or 0.6r. I think 
having these would be nice for user-defined numeric Classes like 
Rational (currently these overload 1/2 under mathn and other operations 
which can be a problem) and imaginary numbers (via the Complex class). I 
think being able to write 0.5r instead of the much longer 
Rational.reduce(1, 2), 2i instead of Complex.new(2, 1) or 5.1b instead 
of BigDecimal.new("5.1") would be a nice thing that would not have many 
downsides.

Peter Vanbroekhoven was able to come up with a fairly simple and 
efficient patch which I have reattached to this mail. With it applied 
you can write 1.5x and it will call number_literal_x("1.5") and return 
the result.

However I might be overlooking issues that are associated with this 
enhancement and I know that having useless features leads to language 
bloat. So what do the community and matz think about this? Would this be 
useful to you?

Thank you all in advance for feedback.

Regards,
Florian Gross


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--- eval.c	13 Oct 2004 19:45:26 -0000	1.1.1.1
+++ eval.c	26 Dec 2004 23:38:50 -0000	1.1.1.1.22.2
@@ -7527,6 +7527,13 @@
     ruby_safe_level = safe;
 }
 
+static VALUE
+rb_number_literal_f(obj, s)
+     VALUE obj, s;
+{
+    return rb_float_new(rb_str_to_dbl(s, Qfalse));
+}
+
 void
 Init_eval()
 {
@@ -7623,6 +7630,8 @@
     rb_global_variable(&trace_func);
 
     rb_define_virtual_variable("$SAFE", safe_getter, safe_setter);
+
+    rb_define_method(rb_mKernel, "number_literal_f", rb_number_literal_f, 1);
 }
 
 /*
--- parse.y	13 Oct 2004 19:46:40 -0000	1.1.1.1
+++ parse.y	26 Dec 2004 23:38:51 -0000	1.1.1.1.22.3
@@ -244,7 +244,7 @@
 	k__FILE__
 
 %token <id>   tIDENTIFIER tFID tGVAR tIVAR tCONSTANT tCVAR
-%token <node> tINTEGER tFLOAT tSTRING_CONTENT
+%token <node> tINTEGER tFLOAT tSTRING_CONTENT tNUMBER_LITERAL
 %token <node> tNTH_REF tBACK_REF
 %token <num>  tREGEXP_END
 
@@ -2131,6 +2131,7 @@
 		;
 
 numeric		: tINTEGER
+                | tNUMBER_LITERAL
 		| tFLOAT
 		| tUMINUS_NUM tINTEGER	       %prec tLOWEST
 		    {
@@ -3923,6 +3924,19 @@
 
 	  decode_num:
 	    pushback(c);
+	    if (nondigit && ISALPHA(nondigit)) {
+	        c = nondigit;
+	    }
+	    if (ISALPHA(c)) {
+	        char name[17] = "number_literal_*";
+		name[15] = c;
+		NODE *str;
+	        tokfix();
+		str = NEW_LIST(NEW_STR(rb_str_new(tok(), toklen())));
+		nextc();
+		yylval.node = NEW_FCALL(rb_intern(name), str);
+		return tNUMBER_LITERAL;
+	    }
 	    tokfix();
 	    if (nondigit) {
 		char tmp[30];
--- ext/bigdecimal/bigdecimal.c	13 Oct 2004 19:48:30 -0000	1.1.1.1
+++ ext/bigdecimal/bigdecimal.c	26 Dec 2004 01:19:20 -0000	1.1.1.1.22.1
@@ -1217,6 +1217,19 @@
 }
 
 static VALUE
+rb_number_literal_b(obj, s)
+     VALUE obj, s;
+{
+    ENTER(5);
+    Real *pv;
+
+    SafeStringValue(s);
+    GUARD_OBJ(pv, VpCreateRbObject(0, RSTRING(s)->ptr));
+    
+    return ToValue(pv);
+}
+
+static VALUE
 BigDecimal_limit(int argc, VALUE *argv, VALUE self)
 {
     VALUE  nFig;
@@ -1346,6 +1359,8 @@
     rb_define_method(rb_cBigDecimal, "finite?",   BigDecimal_IsFinite, 0);
     rb_define_method(rb_cBigDecimal, "truncate",  BigDecimal_truncate, -1);
     rb_define_method(rb_cBigDecimal, "_dump", BigDecimal_dump, -1);
+
+    rb_define_method(rb_mKernel, "number_literal_b", rb_number_literal_b, 1);
 }
 
 /*

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