www.digitalmars.com         C & C++   DMDScript  

digitalmars.D - Re: poll for properties

Steven Schveighoffer Wrote:

 Please respond to this poll before reading other responses.
 
 Read the following function:
 
 void foo(Box b)
 {
    if(b.xxx)
      b.fill(5);
    else
      b.yyy;
 }
 
 Assuming you have no idea what type Box is, what of the following options  
 looks most natural for xxx in order to test to see if b has an element in  
 it?
 
 a) if(b.empty)
 b) if(b.empty())
 c) if(b.clear)
 d) if(b.clear())
 
 Answer:
 =============

a
 =============
 
 What would you guess looks most natural for yyy in order to remove all  
 elements from b?
 
 a) b.empty;
 b) b.empty();
 c) b.clear;
 d) b.clear();
 
 Answer:
 =============

d
 =============
 
 Which of the following functions looks incorrect?
 
 void a(Box box)
 {
     if(box.empty())
       box.fill(5);
     else
       box.clear();
 }
 
 void b(Box box)
 {
     if(box.empty)
       box.fill(5);
     else
       box.clear;
 }
 
 void c(Box box)
 {
      if(box.clear)
         box.fill(5);
      else
         box.empty;
 }
 
 void d(Box box)
 {
      if(box.clear())
         box.fill(5);
      else
         box.empty();
 }
 
 
 Answer:
 ==============

All of them. It's impossible to determine which method clears and which checks for emptyness. I don't like b.yyy; hanging on its own either.
 ==============
 
 You read the documentation for Box, and it looks like this:
 
 /**
   * check to see if a box is clear
   */
   bool clear();
 
 /**
   * empty a box, returning true if the box had contents before emptying
   */
   bool empty();
 
 Now knowing what the actual meaning of clear and empty are, indicate which  
 version(s) of the function in the previous question would surprise you if  
 it compiled.
 
 Here are the functions again for reference:
 
 void a(Box box)
 {
     if(box.empty())
       box.fill(5);
     else
       box.clear();
 }
 
 void b(Box box)
 {
     if(box.empty)
       box.fill(5);
     else
       box.clear;
 }
 
 void c(Box box)
 {
      if(box.clear)
         box.fill(5);
      else
         box.empty;
 }
 
 void d(Box box)
 {
      if(box.clear())
         box.fill(5);
      else
         box.empty();
 }
 
 Answer:
 ==============

Did you mean, which function's behavior would surprise me in run time? Given the functions' code structure there's only one possible way for meaningful operation: if clause checks for emtyness, else clause empties. So the first two functions will surprise.
 ==============
 
 Do you think the meaning of a symbol with parentheses suggests something  
 different than that same symbol without parentheses for the following  
 symbols:
 
 a) select
 b) rock
 c) keyboard
 d) elevate
 
 Answer:
 ==============

a,b,d I remember somewhere verb-like words were used to denote objects...
 ==============

Jul 29 2009