On Aug 22, 2006, at 1:43 AM, Eric Lemings wrote:
-----Original Message----- From: boost-bounces@lists.boost.org [mailto:boost-bounces@lists.boost.org] On Behalf Of Matthias Troyer Sent: Saturday, August 19, 2006 1:55 AM To: boost@lists.boost.org Subject: Re: [boost] Boost Units library preview
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If I understand the above concepts correctly then we only need three terms:
- named unit - unnamed unit - quantity (value + unit)
I try to keep the definitions as simple as possible. IMHO, there are really only four distinct concepts:
dimension - an "abstract" type quantity - an "abstract" object whose "type" is a dimension unit - a type "derived" from a particular dimension measure - an arithmetic object whose "type" is a unit
The last term is a term I introduced to distinguish an object with a dimension from an object with a unit. Very important distinction.
Eric.
Let me check if I understand this correctly in one example. - Nm would be a "dimension" - 1 Nm would be a "quantity" - a torque measured in Nm or an energy measured in Nm would be two distinct units - 1 Nm as torque, 1 Nm as energy or 1 J as energy would be three distinct measures If that is correct then I have several comments, but please check my understanding first. Matthias