Re: [ublas] Not using the default constructor as zero?

From: Gunter Winkler (guwi17_at_[hidden])
Date: 2005-01-25 05:02:47

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On Monday 24 January 2005 20:33, Daryle Walker wrote:
> I don't know much about uBLAS, so sorry if I sound like an uneducated
> newbie.  This sounds like you use "value_type(0)" whenever you need a zero
> value for a type.  What's wrong with "value_type()"?  Every built-in and
> user-defined numeric (scalar) type I know of makes the explicit default
> constructor evaluate its object to zero.  This policy would be easier to
> accept for types that didn't want an "int" constructor.  You have to use
> the explicit syntax because implicit default construction for built-in
> types leaves them as a bucket of random bits (for C compatibility and to
> not add extra code).

We already discussed this issue at the developer meeting. We finally decided 
to use value_type(0) because value_type could be a big algebraic object, e.g. 
a matrix. For matrices there is a big difference between allocating an empty 
matrix using the default constructor and allocating a matrix full of zeroes 
using the "int" constructor. Maybe this behaviour will be replaced by some 
traits classes in a future version of ublas. The traits classes can provide 
other useful information like value_type(1), too.

mfg
Gunter
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