From: Tadashi Saito <shiba@...2.accsnet.ne.jp>
Date: 2003-07-13T00:55:04+09:00
Subject: [ruby-dev:20642] [BigDecimal] 標準添付案

This is a multi-part message in MIME format.

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	charset="iso-2022-jp"
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斎藤です。

----- Original Message ----- 
From: "石塚圭樹" <keiju@ishitsuka.com>
Sent: Saturday, July 12, 2003 5:36 AM
Subject: [ruby-dev:20637] [BigDecimal] 標準添付案 [Re: Re: [BigDecimal]
renaming proposal]

> sin/cos/**などの関数は省いて四則演算などの基本的な演算のみにする. これ
> は, すでにそういう方針で行こうとしていますよね.

あれ、** も省くのでしたっけ。
それとも Bigdecimal ** Bigdecimalはできない、という話でしょうか。

> あと, coerceですが,
>
> まず, Stringとのcoerceは絶対なし. BigDecimalの簡略した表現(リテラル)な
> ど別スレッドで話題になっていますが, これらがボツになってもです.
>
> # 松本さんのメイル[ruby-dev:20630]は良く理解できなかったですが, 同じと
> # ころを指しているのでは? とかってにそうぞうしていす.

ここの解釈は合っていると思います。

> つぎに, Floatとのcoerceはやめた方が良いと思います. たぶん,小林さんも
> FloatとBigDecimalを直接演算させることはやってない思います. Floatから
> BigDecimalに変換するのにビミョーな誤差がでるので暗黙的変換はかなり使い
> づらいからです. ですので, Float - > BigDecimalは明示的変換にする方が良
> い(つまり, 使う本人がわかって使うぶんには良い)と思います.

自分も賛成です。自分も、Floatとのcoerceを話題にしようか
悩んでいた所でした。

・StringやFloatのcoerceの削除
・FloatからBigDecimalへの明示的な変換の実装(Float#to_d)
・それらに伴う添付文章の削除・追加

を含むパッチを、以前のString#to_d等とマージして、メールに添付して
みました。よかったら使ってください。

> あと, クラス名ですね. BigDecimalでもまあ良いと思いますが, BigDecimalは
> Floatの代わりになるものであり、10進系を強調するとすればBigをとって
> Decimal または Decimalnum, Decinum みたいのが良いと思います。 逆に
> BigDecimalというと FloatのBigなもをイメージするのであまりよくないかな
> と...

実は自分も同じようなことを考えていました。もし改名が許されるなら、
自分は「Decimal」がいいと思います。数に対して「Big」という形容詞をつけるの
なら、値が大きいということを意味するのが自然だと思いますが、
(Bignumとは違って)BigDecimalはそうとは限らないからです。
またDecimalなら「小数」「10進」両方の意味を持っているので、それだけで
十分意味を語れると思います。

---
斎藤ただし

------=_NextPart_000_00ED_01C348D9.659F7D00
Content-Type: application/octet-stream;
	name="to_d.patch"
Content-Transfer-Encoding: quoted-printable
Content-Disposition: attachment;
	filename="to_d.patch"

? o=0A=
? lib/o=0A=
Index: bigdecimal.c=0A=
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=0A=
RCS file: /src/ruby/ext/bigdecimal/bigdecimal.c,v=0A=
retrieving revision 1.9=0A=
diff -u -r1.9 bigdecimal.c=0A=
--- bigdecimal.c	1 Jul 2003 14:14:18 -0000	1.9=0A=
+++ bigdecimal.c	12 Jul 2003 15:26:58 -0000=0A=
@@ -135,7 +135,6 @@=0A=
 static Real *=0A=
 GetVpValue(VALUE v, int must)=0A=
 {=0A=
-    double dv;=0A=
     Real *pv;=0A=
     VALUE bg;=0A=
     char szD[128];=0A=
@@ -153,40 +152,6 @@=0A=
     case T_FIXNUM:=0A=
         sprintf(szD, "%d", FIX2INT(v));=0A=
         return VpCreateRbObject(VpBaseFig() * 2 + 1, szD);=0A=
-    case T_FLOAT:=0A=
-        pv =3D VpCreateRbObject(VpDblFig()*2,"0");=0A=
-        dv =3D RFLOAT(v)->value;=0A=
-        /* From float */=0A=
-        if (isinf(dv)) {=0A=
-            VpException(VP_EXCEPTION_INFINITY,"Computation including =
infinity",0);=0A=
-            if(dv=3D=3DVpGetDoublePosInf()) {=0A=
-                VpSetPosInf(pv);=0A=
-            } else {=0A=
-                VpSetNegInf(pv);=0A=
-            }=0A=
-        } else=0A=
-        if (isnan(dv)) {=0A=
-            VpException(VP_EXCEPTION_NaN,"Computation including NaN(Not =
a number)",0);=0A=
-            VpSetNaN(pv);=0A=
-        } else {=0A=
-            if (VpIsNegDoubleZero(dv)) {=0A=
-                VpSetNegZero(pv);=0A=
-            } else if(dv=3D=3D0.0) {=0A=
-                VpSetPosZero(pv);=0A=
-            } else if(dv=3D=3D1.0) {=0A=
-                VpSetOne(pv);=0A=
-            } else if(dv=3D=3D-1.0) {=0A=
-                VpSetOne(pv);=0A=
-                pv->sign =3D -pv->sign;=0A=
-            } else {=0A=
-                VpDtoV(pv,dv);=0A=
-            }=0A=
-        }=0A=
-        return pv;=0A=
-    case T_STRING:=0A=
-        SafeStringValue(v);=0A=
-        return VpCreateRbObject(strlen(RSTRING(v)->ptr) + VpBaseFig() + =
1,=0A=
-                                RSTRING(v)->ptr);=0A=
     case T_BIGNUM:=0A=
         bg =3D rb_big2str(v, 10);=0A=
         return VpCreateRbObject(strlen(RSTRING(bg)->ptr) + VpBaseFig() =
+ 1,=0A=
@@ -1253,6 +1218,81 @@=0A=
     return obj;=0A=
 }=0A=
 =0A=
+static VALUE=0A=
+str_to_d(VALUE str)=0A=
+{=0A=
+    ENTER(1);=0A=
+    Real *a;=0A=
+=0A=
+    SafeStringValue(str);=0A=
+    GUARD_OBJ(a, VpCreateRbObject(strlen(RSTRING(str)->ptr) + =
VpBaseFig() + 1,=0A=
+                                RSTRING(str)->ptr));=0A=
+    return ToValue(a);=0A=
+}=0A=
+=0A=
+static VALUE=0A=
+fix_to_d(VALUE num)=0A=
+{=0A=
+    ENTER(1);=0A=
+    Real *a;=0A=
+    char szD[128];=0A=
+=0A=
+    sprintf(szD, "%d", FIX2INT(num));=0A=
+    GUARD_OBJ(a,VpCreateRbObject(VpBaseFig() * 2 + 1, szD));=0A=
+    return ToValue(a);=0A=
+}=0A=
+=0A=
+static VALUE=0A=
+big_to_d(VALUE x)=0A=
+{=0A=
+    ENTER(1);=0A=
+    Real *a;=0A=
+    VALUE bg;=0A=
+=0A=
+    bg =3D rb_big2str(x, 10);=0A=
+    GUARD_OBJ(a,VpCreateRbObject(strlen(RSTRING(bg)->ptr) + VpBaseFig() =
+ 1,=0A=
+				 RSTRING(bg)->ptr));=0A=
+    return ToValue(a);=0A=
+}=0A=
+=0A=
+static VALUE=0A=
+flo_to_d(num)=0A=
+    VALUE num;=0A=
+{=0A=
+    ENTER(1);=0A=
+    Real *pv;=0A=
+    double dv;=0A=
+=0A=
+    GUARD_OBJ(pv,VpCreateRbObject(VpDblFig()*2,"0"));=0A=
+    dv =3D RFLOAT(num)->value;=0A=
+    if (isinf(dv)) {=0A=
+	VpException(VP_EXCEPTION_INFINITY,"Computation including infinity",0);=0A=
+	if(dv=3D=3DVpGetDoublePosInf()) {=0A=
+	    VpSetPosInf(pv);=0A=
+	} else {=0A=
+	    VpSetNegInf(pv);=0A=
+	}=0A=
+    } else=0A=
+    if (isnan(dv)) {=0A=
+	VpException(VP_EXCEPTION_NaN,"Computation including NaN(Not a =
number)",0);=0A=
+	VpSetNaN(pv);=0A=
+    } else {=0A=
+	if (VpIsNegDoubleZero(dv)) {=0A=
+	    VpSetNegZero(pv);=0A=
+	} else if(dv=3D=3D0.0) {=0A=
+	    VpSetPosZero(pv);=0A=
+	} else if(dv=3D=3D1.0) {=0A=
+	    VpSetOne(pv);=0A=
+	} else if(dv=3D=3D-1.0) {=0A=
+	    VpSetOne(pv);=0A=
+	    pv->sign =3D -pv->sign;=0A=
+	} else {=0A=
+	    VpDtoV(pv,dv);=0A=
+	}=0A=
+    }=0A=
+    return ToValue(pv);=0A=
+}=0A=
+=0A=
 =0A=
 #ifdef USE_MUTABLE_METHOD=0A=
 /**** Following methods are all MUTABLE and not currently activated. =
****/=0A=
@@ -1450,6 +1490,12 @@=0A=
     rb_define_method(rb_cBigDecimal, "finite?",   BigDecimal_IsFinite, =
0);=0A=
     rb_define_method(rb_cBigDecimal, "truncate",  BigDecimal_truncate, =
-1);=0A=
     rb_define_method(rb_cBigDecimal, "_dump", BigDecimal_dump, -1);=0A=
+=0A=
+    /* misc utility methods */=0A=
+    rb_define_method(rb_cString, "to_d", str_to_d, 0);=0A=
+    rb_define_method(rb_cFixnum, "to_d", fix_to_d, 0);=0A=
+    rb_define_method(rb_cBignum, "to_d", big_to_d, 0);=0A=
+    rb_define_method(rb_cFloat, "to_d", flo_to_d, 0);=0A=
 =0A=
 #ifdef USE_MUTABLE_METHOD=0A=
     rb_define_singleton_method(rb_cBigDecimal, "assign!", =
BigDecimal_assign, 3);=0A=
Index: bigdecimal_en.html=0A=
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=0A=
RCS file: /src/ruby/ext/bigdecimal/bigdecimal_en.html,v=0A=
retrieving revision 1.4=0A=
diff -u -r1.4 bigdecimal_en.html=0A=
--- bigdecimal_en.html	27 Jun 2003 04:38:57 -0000	1.4=0A=
+++ bigdecimal_en.html	12 Jul 2003 15:26:58 -0000=0A=
@@ -97,7 +97,8 @@=0A=
 "new" method creates a new BigDecimal object.<BR>=0A=
 a=3DBigDecimal::new(s[,n])<BR>=0A=
 where:<BR>=0A=
-s: Initial value string.<BR>=0A=
+s: Initial value string. "Infinity", "+Infinity", "-Infinity", and =
"NaN" can also be used unless false is specified by mode method.=0A=
+<BR>=0A=
 n: Maximum number of significant digits of a. n must be a Fixnum object.=0A=
 If n is omitted or is equal to 0,then the maximum number of significant =
digits of a is determined from the length of s.=0A=
 </BLOCKQUOTE>=0A=
@@ -507,6 +508,12 @@=0A=
 <LI>&gt;</LI>=0A=
 <LI>&gt;=3D</LI>=0A=
 </UL>=0A=
+<H4><U>Instance methods in other classes</U></H4>=0A=
+<UL>=0A=
+<LI><B>String#to_d, Fixnum#to_d, Bignum#to_d, =
Float#to_d</B></LI><BLOCKQUOTE>=0A=
+returns BigDecimal value equivalent to the value of receiver.=0A=
+</BLOCKQUOTE>=0A=
+</UL>=0A=
 <HR>=0A=
 =0A=
 <H3>About 'coerce'</H3>=0A=
@@ -520,30 +527,6 @@=0A=
 <DD>If A has coerce mthod,then B will translate A to corresponding =0A=
 BigDecimal object and the operation is performed,otherwise an error =
occures.</DD>=0A=
 </DL>=0A=
-=0A=
-Attention must be paid when a String is to be translated to BigDecimal.=0A=
-Translation stops without error at the character representing non digit.=0A=
-For instance,"10XX" is translated to 10,"XXXX" is translated to 0.<BR>=0A=
-String representing zero or infinity such as =
"Infinity","+Infinity","-Infinity",and "NaN" can also be translated to =
BigDecimal unless false is specified by mode method.<BR>=0A=
-=0A=
-BigDecimal class supports coerce method(for the details about coerce =
method,see Ruby documentations). This means the most binary operation =
can be performed if the BigDecimal object is at the left hand side of =
the operation.<BR><BR>=0A=
-=0A=
- For example:=0A=
-<CODE><PRE>=0A=
-  a =3D BigDecimal.E(20)=0A=
-  c =3D a * "0.123456789123456789123456789" # A String is changed to =
BigDecimal object.=0A=
-</PRE></CODE>=0A=
-is performed normally.<BR>=0A=
- But,because String does not have coerce method,the following example =
can not be performed.<BR>=0A=
-=0A=
-<CODE><PRE>=0A=
-  a =3D BigDecimal.E(20)=0A=
-  c =3D "0.123456789123456789123456789" * a # ERROR=0A=
-</PRE></CODE>=0A=
-=0A=
-If you actually have any inconvenience about the error above.=0A=
-You can define a new class derived from String class,=0A=
-and define coerce method within the new class.<BR>=0A=
 =0A=
 <hr>=0A=
 <A NAME=3D"#UNDEF">=0A=
Index: bigdecimal_ja.html=0A=
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=0A=
RCS file: /src/ruby/ext/bigdecimal/bigdecimal_ja.html,v=0A=
retrieving revision 1.4=0A=
diff -u -r1.4 bigdecimal_ja.html=0A=
--- bigdecimal_ja.html	27 Jun 2003 04:38:57 -0000	1.4=0A=
+++ bigdecimal_ja.html	12 Jul 2003 15:26:58 -0000=0A=
@@ -104,7 +104,10 @@=0A=
 <LI><B>new</B></LI><BLOCKQUOTE>=0A=
 =90V=82=B5=82=A2 BigDecimal =
=83I=83u=83W=83F=83N=83g=82=F0=90=B6=90=AC=82=B5=82=DC=82=B7=81B<BR>=0A=
 a=3DBigDecimal::new(s[,n])<BR>=0A=
-s =
=82=CD=8F=89=8A=FA=92l=82=F0=95=B6=8E=9A=97=F1=82=C5=8Ew=92=E8=82=B5=82=DC=
=82=B7=81D=0A=
+s =
=82=CD=8F=89=8A=FA=92l=82=F0=95=B6=8E=9A=97=F1=82=C5=8Ew=92=E8=82=B5=82=DC=
=82=B7=81D=96=B3=8C=C0=91=E5=82=E2=94=F1=90=94=82=F0=95\=82=B7=95=B6=8E=9A=
=82=C6=82=B5=82=C4=81A=0A=
+"Infinity"=81A"+Infinity"=81A"-Infinity"=81A"NaN"=82=E0=8Eg=97p=82=C5=82=
=AB=82=DC=82=B7=0A=
+(=91=E5=95=B6=8E=9A=81E=8F=AC=95=B6=8E=9A=82=F0=8B=E6=95=CA=82=B5=82=DC=82=
=B7)=81B=82=BD=82=BE=82=B5=81Amode =83=81=83\=83b=83h=82=C5 false =82=F0=0A=
+=8Ew=92=E8=82=B5=82=BD=8F=EA=8D=87=82=CD=97=E1=8AO=82=AA=94=AD=90=B6=82=B5=
=82=DC=82=B7=81B<BR>=0A=
 n =82=CD=95K=97v=82=C8=97L=8C=F8=8C=85=90=94=81ia =
=82=CC=8D=C5=91=E5=97L=8C=F8=8C=85=90=94=81j=82=F0=90=AE=90=94=82=C5=8Ew=92=
=E8=82=B5=82=DC=82=B7=81B=0A=
 n =82=AA 0 =
=82=DC=82=BD=82=CD=8F=C8=97=AA=82=B3=82=EA=82=BD=82=C6=82=AB=82=CD=81An =
=82=CC=92l=82=CD s =
=82=CC=97L=8C=F8=8C=85=90=94=82=C6=82=DD=82=C8=82=B3=82=EA=82=DC=82=B7=81=
B=0A=
 s =82=CC=97L=8C=F8=8C=85=90=94=82=E6=82=E8 n =
=82=AA=8F=AC=82=B3=82=A2=82=C6=82=AB=82=E0 n=3D0 =
=82=CC=82=C6=82=AB=82=C6=93=AF=82=B6=82=C5=82=B7=81B=0A=
@@ -493,32 +496,17 @@=0A=
 <LI><B>&gt</B></LI>=0A=
 <LI><B>&gt=3D</B></LI>=0A=
 </UL>=0A=
+<H4><U>=91=BC=83N=83=89=83X=82=CC=83C=83=93=83X=83^=83=93=83X=83=81=83\=83=
b=83h</U></H4>=0A=
+<UL>=0A=
+<LI><B>String#to_d, Fixnum#to_d, Bignum#to_d, =
Float#to_d</B></LI><BLOCKQUOTE>=0A=
+=82=BB=82=EA=82=BC=82=EA=82=CC=83=8C=83V=81[=83o=82=CC=92l=82=C9=91=CE=89=
=9E=82=B7=82=E9BigDecimal=82=F0=95=D4=82=B5=82=DC=82=B7=81B=0A=
+</BLOCKQUOTE>=0A=
+</UL>=0A=
 <H3>coerce=82=C9=82=C2=82=A2=82=C4</H3>=0A=
 BigDecimal =
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 =
=89E=82=C9=82=A0=82=E9=83I=83u=83W=83F=83N=83g=82=F0(=95K=97v=82=C8=82=E7=
) BigDecimal =
=82=C9=95=CF=8A=B7=82=B5=82=C4=82=A9=82=E7=8Cv=8EZ=82=B5=82=DC=82=B7=81B=0A=
 =8F]=82=C1=82=C4=81ABigDecimal =
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=82=B7=82=E9=82=E0=82=CC=82=C8=82=E7=89E=82=C9=92u=82=AF=82=CE=0A=
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=C5=82=AB=82=C8=82=A2=95=B6=8E=9A=82=AA=82=A0=82=E9=82=C6=81A=0A=
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=81[=82=C9=82=CD=82=C8=82=E8=82=DC=82=B9=82=F1=81B"10XX"=82=C8=82=E7=82P=82=
O=81A"XXXX"=82=CD=82O=0A=
-=82=C6=88=B5=82=ED=82=EA=82=DC=82=B7=81B<BR>=0A=
-<CODE><PRE>=0A=
-   a =3D BigDecimal.E(20)=0A=
-   c =3D a * "0.123456789123456789123456789" # =95=B6=8E=9A=82=F0 =
BigDecimal =82=C9=95=CF=8A=B7=82=B5=82=C4=82=A9=82=E7=8Cv=8EZ=0A=
-</PRE></CODE>=0A=
-=96=B3=8C=C0=91=E5=82=E2=94=F1=90=94=82=F0=95\=82=B7=95=B6=8E=9A=82=C6=82=
=B5=82=C4=81A"Infinity"=81A"+Infinity"=81A"-Infinity"=81A"NaN"=0A=
-=82=E0=8Eg=97p=82=C5=82=AB=82=DC=82=B7(=91=E5=95=B6=8E=9A=81E=8F=AC=95=B6=
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B<BR>=0A=
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-  a =3D BigDecimal.E(20)=0A=
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- String =
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-=82=BB=82=CC=83N=83=89=83X=82=C5 coerce =
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 =0A=
 <hr>=0A=
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