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Re: bitwise ORing

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Don Y wrote:
> Hi Bill,
> 
> On 3/22/2012 6:56 PM, Bill Cunningham wrote:
>>      What would a function prototype look like that takes one
>> parameter but several options can be OR'd together in that
>> parameter? For example: 
>> 
>> function(LEFT|RIGHT);
>> 
>> What would the parameter source code look like?
> 
> Usually, this is an integer (of some size) data type.
> The manifest constants LEFT and RIGHT are typically disjoint
> bitsets (though they need not be).  They can also be derived
> from an enumerated type, etc.
> 
> E.g., render_text(const char *string, attr_t attributes)
> 
> where:
>    attributes ::= BLINK | BOLD | DIM | INVISIBLE | ITALIC | etc.
> 
> (note my use of '|' here is in the context of a BNF, not a
> C statement; also, this specfication says nothing about how
> "sensible" BLINK | INVISIBLE might be!  :> )
> 
> So,
>    render_text("Big SALE today!!", BOLD | BLINK);
> one of the semantic problems with the use of "or" is that it
> really is implementing what you would COLLOQUIALLY think of
> as an "and" function:  "Make this BOLD *and* BLINKing".

#define and |  /* ;-) */
...
render_text("Big SALE today!!", BOLD and BLINK);

Bye, Jojo

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bitwise ORing "Bill Cunningham" <nospam@nspam.invalid> - 2012-03-22 20:56 -0500
  Re: bitwise ORing pete <pfiland@mindspring.com> - 2012-03-22 21:29 -0500
  Re: bitwise ORing Lew Pitcher <lpitcher@teksavvy.com> - 2012-03-23 11:19 -0400
    Re: bitwise ORing James Kuyper <jameskuyper@verizon.net> - 2012-03-23 11:43 -0400
    Re: bitwise ORing "Bill Cunningham" <nospam@nspam.invalid> - 2012-03-23 16:23 -0500
    Re: bitwise ORing "Bill Cunningham" <nospam@nspam.invalid> - 2012-03-25 13:02 -0500
      Re: bitwise ORing Lew Pitcher <lpitcher@teksavvy.com> - 2012-03-25 16:26 -0400
  Re: bitwise ORing jgk@panix.com (Joe keane) - 2012-03-23 20:31 +0000
  Re: bitwise ORing Don Y <this@isnotme.com> - 2012-03-23 13:41 -0700
    Re: bitwise ORing "Joachim Schmitz" <nospam.jojo@schmitz-digital.de> - 2012-03-24 11:29 +0100
      Re: bitwise ORing Geoff <geoff@invalid.invalid> - 2012-03-24 19:06 -0700

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