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From: BRYAN@SU-SIERRA.ARPA (Doug Bryan)
Newsgroups: net.lang.ada
Subject: put ("i = " & x);
Message-ID: <8509200641.AA07544@UCB-VAX.ARPA>
Date: Fri, 20-Sep-85 01:43:04 EDT
Article-I.D.: UCB-VAX.8509200641.AA07544
Posted: Fri Sep 20 01:43:04 1985
Date-Received: Sun, 22-Sep-85 05:50:16 EDT
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As usual, Dr. Helfinger has brought up some very good points.
When Ada cannot do what you want it to do, explain the problem
better (implement a package - extensability).

The following package and demo main-line demonstrates his ideas.
To "fully" implement this capability, the package should also contain
the full capabilities of Text_Io so that default aft, exp, file_type...
may be used.

The output version here is fairly trivial.  Anybody have any ideas
on the input version keeping 4.3(7) in mind??????

doug

   ----------------------------------------------------------

with Text_Io;

generic
    type Int  is range <>;
    type Enum is (<>);
    type Fl   is digits <>;
    type Fx   is delta <>;
package Poly_Images is

    function "&" (Left : String; Right : Int) return String;
    function "&" (Left : Int; Right : String) return String;
    function Fmt (I     : Int;
		  Width : Text_Io.Field;
		  Base  : Text_Io.Number_Base) return String;

    function "&" (Left : String; Right : Enum) return String;
    function "&" (Left : Enum; Right : String) return String;
    function Fmt (E     : Enum;
		  Width : Text_Io.Field;
		  Set   : Text_Io.Type_Set) return String;

    function "&" (Left : String; Right : Fl) return String;
    function "&" (Left : Fl; Right : String) return String;
    function Fmt (F               : Fl;
		  Width, Aft, Exp : Text_Io.Field) return String;

    function "&" (Left : String; Right : Fx) return String;
    function "&" (Left : Fx; Right : String) return String;
    function Fmt (F               : Fx;
		  Width, Aft, Exp : Text_Io.Field) return String;

end Poly_Images;
   ----------------------------------------------------------

with Text_Io;
package body Poly_Images is

    package Int_Io is new Text_Io.Integer_Io (Int);
    package Enum_Io is new Text_Io.Enumeration_Io (Enum);
    package Fl_Io is new Text_Io.Float_Io (Fl);
    package Fx_Io is new Text_Io.Fixed_Io (Fx);

    function "&" (Left : String; Right : Int) return String is
    begin
	return Left & Int'Image (Right);
    end "&";

    function "&" (Left : Int; Right : String) return String is
    begin
	return Int'Image (Left) & Right;
    end "&";

    function "&" (Left : String; Right : Enum) return String is
    begin
	return Left & Enum'Image (Right);
    end "&";

    function "&" (Left : Enum; Right : String) return String is
    begin
	return Enum'Image (Left) & Right;
    end "&";

    function Strip_Leading_Blanks (Within : String) return String is
    begin
	for I in Within'Range loop
	    if Within (I) /= ' ' then
		if Within (I) = '-' or
		   Within (I) = '+' or
		   Within (I) not in '0' .. '9' then
		    return Within (I .. Within'Last);
		else
		    return Within (I - 1 .. Within'Last);
		end if;
	    end if;
	end loop;
	return "";
    exception
	when Constraint_Error => 
	    return Within;
    end Strip_Leading_Blanks;

    function "&" (Left : String; Right : Fl) return String is
	Image : String (1 .. 300);
    begin
	Fl_Io.Put (To => Image, Item => Right);
	return Left & Strip_Leading_Blanks (Image);
    end "&";

    function "&" (Left : Fl; Right : String) return String is
	Image : String (1 .. 300);
    begin
	Fl_Io.Put (To => Image, Item => Left);
	return Strip_Leading_Blanks (Image) & Right;
    end "&";

    function "&" (Left : String; Right : Fx) return String is
	Image : String (1 .. 300);
    begin
	Fx_Io.Put (To => Image, Item => Right);
	return Left & Strip_Leading_Blanks (Image);
    end "&";

    function "&" (Left : Fx; Right : String) return String is
	Image : String (1 .. 300);
    begin
	Fx_Io.Put (To => Image, Item => Left);
	return Strip_Leading_Blanks (Image) & Right;
    end "&";

    function Fmt (I     : Int;
		  Width : Text_Io.Field;
		  Base  : Text_Io.Number_Base) return String is
	Image : String (1 .. 300);
    begin
	if Width = 0 then
	    Int_Io.Put (Image, I, Base);
	    return Strip_Leading_Blanks (Image);
	else
	    Int_Io.Put (Image (1 .. Width), I, Base);
	    return Image (1 .. Width);
	end if;
    end Fmt;

    function Fmt (E     : Enum;
		  Width : Text_Io.Field;
		  Set   : Text_Io.Type_Set) return String is
	Image : String (1 .. 300);
    begin
	if Width = 0 then
	    Enum_Io.Put (Image, E, Set);
	    return Strip_Leading_Blanks (Image);
	else
	    Enum_Io.Put (Image (1 .. Width), E, Set);
	    return Image (1 .. Width);
	end if;
    end Fmt;

    function Fmt (F               : Fl;
		  Width, Aft, Exp : Text_Io.Field) return String is
	Image : String (1 .. 300);
    begin
	if Width = 0 then
	    Fl_Io.Put (Image, F, Aft, Exp);
	    return Strip_Leading_Blanks (Image);
	else
	    Fl_Io.Put (Image (1 .. Width), F, Aft, Exp);
	    return Image (1 .. Width);
	end if;
    end Fmt;

    function Fmt (F               : Fx;
		  Width, Aft, Exp : Text_Io.Field) return String is
	Image : String (1 .. 300);
    begin
	if Width = 0 then
	    Fx_Io.Put (Image, F, Aft, Exp);
	    return Strip_Leading_Blanks (Image);
	else
	    Fx_Io.Put (Image (1 .. Width), F, Aft, Exp);
	    return Image (1 .. Width);
	end if;
    end Fmt;

end Poly_Images;
   ----------------------------------------------------------

with Text_Io,
     Poly_Images;
use Text_Io;

procedure Poly_Images_Test is
    package Images is new Poly_Images
	       (Int  => Integer,
		Enum => Boolean,
		Fl   => Float,
		Fx   => Duration);
    use Images;

    I  : Integer;
    Fp : Float;
    Fd : Duration;
    E  : Boolean;
begin
    I := 12;  Fp := 12.12;  Fd := 1.0102;  E := True;
    Put_Line ("integer = " & I & ", floating = " & Fp &
	      ", fixed = " & Fd & ", enumation = " & E);

    I := -12;  Fp := -12.12;  Fd := -1.0102;  E := False;
    Put_Line ("integer = " & I & ", floating = " & Fp &
	      ", fixed = " & Fd & ", enumeration = " & E);
    Put_Line ("integer = " & Fmt (I, 10, 8) & ", floating = " &
	      Fmt (Fp, 10, 2, 0) & "," );
    Put_Line ("       fixed = " &
	      Fmt (Fd, 10, 4, 0) & ", enumeration = " &
	      Fmt (E, 10, Lower_Case));

exception
    when others => 
	New_Line;
	Put_Line ("Fatal exception propagation.");
end Poly_Images_Test;

pragma Main;
-------