OpenEuphoria

Re: booleans

• Posted by David Cuny <dcuny at LANSET.COM> Feb 05, 2001
• 474 views

Kat wrote:

> result = ""
> if ( result = "" ) then
> if equal(result,"") then

If I write:

   object result
   result = ""
   if equal( result, "" ) then
       puts( 1, "empty" )
   else
       puts( 1, "not empty" )
   end if

it will run correctly. It's only if I comment out the line:

   -- result = ""

that I get an error. I can only assume that, in fact, result is not getting
assigned before the if statement, just like Euphoria is telling you.

I believe the larger question (how can I tell that a variable is unassigned)
is: you can't without crashing your code. One option would be to initialize
your variables to a different data type. For example, if you were dealing
with strings, you could write:

   object string
   string = -1
   ...
   if equal( string, -1 ) then
      puts( 1, "string is not initialized.\n" )
      abort(0)
   end if

For example, see gets() and dir().

These sorts of things are prone to causing errors, though. For example, I
always expect dir() to return an empty sequence instead of -1. And I never
catch that kind of bug until after the code has been released...

-- David Cuny