OpenEuphoria

Re: Testing for NULL

• Posted by ghaberek (admin) Sep 04, 2015
• 1905 views

I propose naming these new types with CamelCase, vis-a-vis the string type and String class in C#.

IMHO, this looks cleaner than adding "_or_0" to the type name.

It would also be helpful to have "is null or empty" functions for these new types.

include std/dll.e -- includes NULL 
include std/types.e -- includes string type 
 
-- 
-- returns 1 if x is NULL 
-- 
public function IsNull( object x ) 
    return equal( x, NULL ) 
end function 
 
-- 
-- returns 1 if length(x) = 0 
-- 
public function IsEmpty( object x ) 
    return sequence( x ) and length( x ) = 0 
end function 
 
-- 
-- returns 1 if a x is NULL or length(x) = 0 
-- 
public function IsNullOrEmpty( object x ) 
    return IsNull( x ) or IsEmpty( x ) 
end function 
 
-- 
-- a sequence type that allows NULL 
-- 
public type Sequence( object x ) 
    return sequence( x ) or equal( x, NULL ) 
end type 
 
-- 
-- a string type that allows NULL 
-- 
public type String( object x ) 
    return string( x ) or equal( x, NULL ) 
end type 

Example:

String myName = NULL  -- valid 
 
if IsNullOrEmpty( myName ) then 
    myName = "John Smith" -- valid 
end if 
 
myName = 3.14159      -- invalid 

-Greg