OpenEuphoria

Re: Properties in Methodica

• Posted by Mike Nelson <mikestar13 at sbcglobal.net> Sep 29, 2006
• 578 views

Reposting after a premature send.

Derek Parnell wrote:

> I take it that the 'value' parameter for the setter method is a reserved word
> in that context and is a Euphoria object datatype. That would mean that the
> setter could receive a sequence and deal with as required.

Not quite what I had in mind, but a good idea: value is indeed as reseveved
word in context, but I had assumed that it would have the type of the property.
How about this variant:


property height
public integer get        
   return this.h
public any set
   if not value.is(integer) then
value=value.to_integer() -- Will throw an exception if value can't be
       converted.
   end if
   if value<0 then
       throw Type_Error.new("Height must not be negative.")
   else
       this.h=value            
   end if
end property
 
foo.height = "23"


My original syntax would still be available for the ususal case where both the
getter and the setter are using the same type. Logically it should aso be legal
to put the access specifier after "property" when the same access is desired
for both get and set.
lines 1, 2, and 4 could be written as

property public height
integer get
any set

The type "any" is Methodica's top level generic type, for compatibility with Eu,
object is the supertype of atom, sequence, and thier subtypes.

Methodica types may be value types: object, atom, sequence, string, integer,
etc.
or reference types (classes): Entity, Exception, etc. By convention value types
start with a lowercase letter while reference types start with an uppercased
letter. (The compiler will not enforce this.)

"any" is the lone type which may hold a reference or a value.