Why is it that C++ accepts default parqameters starting from the end of
the parameter list only?

Consider:

void print(char*s, int x=0, int y=0, int color=-1)

This function should use the current cursor coordinates if x or y is
unsecified, and some default color if color is unspecified.

Now, I can call

print("testing",4);

to print starting from column 4 at the current line in the default
color, or even

print("testing");

to continue from current position in current color.

However, I think C++ should also allow this case:

print("testing",,,2);

where x and y are unspecified and color == 2.  Is this possible to
add into the C++ standard, or will empty parameters in the middle of
the list mess up things?

In any case, what is the most elegant way of working around this,
so that the user doesn't have to know what the default values are?

--
Robert Schmidt - robert@alkymi.unit.no - Buuud@IRC
Ztiff Zox Softwear: fast/tiny utilities, games/graphics programming on
                    the DOS platform (C/C++ & asm).  Suggestions welcome!

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In <1993Feb25.155814.1094@ugle.unit.no> robert@alkymi.unit.no (Robert Schmidt) writes:

>Why is it that C++ accepts default parqameters starting from the end of
>the parameter list only?

 [example elided]

>Is this possible to
>add into the C++ standard, or will empty parameters in the middle of
>the list mess up things?

 ARM, p. 142, very top.

>In any case, what is the most elegant way of working around this,
>so that the user doesn't have to know what the default values are?

 The default should be the most natural or most-often used
 value.  If you find users having to know what the default is,
 perhaps it ought not to be default.
--
 - Paul J. Lucas
   AT&T Bell Laboratories
   Naperville, IL

In article <1993Feb25.155814.1094@ugle.unit.no> robert@alkymi.unit.no (Robert Schmidt) writes:

   >>Why is it that C++ accepts default parqameters starting from the end of
   >>the parameter list only?
   >>Consider:
   >>void print(char*s, int x=0, int y=0, int color=-1)

   >>However, I think C++ should also allow this case:
   >>print("testing",,,2);


You should have a screen or cursor object. (... this is the c++ news group)

How about:
  screen.move_cursor(10,20);
  screen.print("testing",2);

You can call several messages if you declare member functions returning
reference of object:

 class Screen {
 public:
  Screen& move_corsor(int,int);
  Screen& print(char* s,int color=-1);
  ...
 };

 screen.move_cursor(10,20).print("testing");




--
Kazuyuki Hagiwara @ Zuken, Inc.  Yokohama, Japan (hagiwara@zuken.co.jp)