Re: [gobo-eiffel-develop] MA_DECIMAL_CONSTANTS.zero

[Eric B. <er...@go...>]

CRISMER Paul-Georges wrote:
> {MA_DECIMAL}.make_zero creates one object whose value is zero.
> That way, 1 million of objects whose value is zero.
> 
> {MA_DECIMAL_CONSTANTS}.zero refers to a single object whose value is
> zero.
> You can have as many references to {MA_DECIMAL}.zero or
> {MA_DECIMAL_CONSTANTS}.zero, they refer all to a unique object whose
> value is zero.
> 
> In {MA_DECIMAL_CONSTANTS}.zero, you have to create a {MA_DECIMAL}
> instance (line 1:) before being able to call the {MA_DECIMAL}.zero
> feature (line 2:).
> 
> Since this object is just a "proxy" to be able to call the
> {MA_DECIMAL}.zero feature, I chose to write line 1: which creates a
> decimal object with 1 significant digit.
> 
> Does this make sense to you?

It does not make sense to me. In your implementation you have
a recursive call to the once function to define it.

I think that what Berend meant was something like:

	zero: MA_DECIMAL is
			-- Neutral element for "+" and "-"
		once
			create Result.make_zero
		ensure
			zero_not_void: Result /= Void
		end

As far as I can tell we don't create a million objects and
the implementation of `zero' is not recursive anymore.

-- 
Eric Bezault
mailto:er...@go...
http://www.gobosoft.com