Re: floating point number wrapper

From:

kenyon <pjzjchn@gmail.com>

Newsgroups:

comp.lang.c++.moderated

Date:

Tue, 3 Jun 2008 10:00:57 CST

Message-ID:

<7b9152f8-9695-4811-bb3c-e0ba8800824c@l17g2000pri.googlegroups.com>

On 6??3??, ????11??00??, "Hicham Mouline" <hic...@mouline.org> wrote:

hello,

I am trying to define a double wrapper that wraps only >=0.0 doubles,

class double_constant_wrapper {
public:
  explicit spot_rate_constant(double r);
  double operator()() const;
  double& operator=(double r);
private:
double r_;

};

inline double_constant_wrapper::double_constant_wrapper(double r)
: r_(r)
{
  if (r<0.0)
    throw exception("number cannot be <0");

}

inline double double_constant_wrapper::operator() const
{
  return r_;

}

inline double& double_constant_wrapper::operator=(double r)
{
  return r_=r;

}

If the user attempts to construct a double_constant_wrapper with a <0.0
double, she will get an exception.
Do the members signatures seem ok?

rds,

I think it's ok.

inline double_constant_wrapper::double_constant_wrapper(double r)
: r_(r)
{
if (r<0.0)
throw exception("number cannot be <0");

}

  the compiler maybe transform this code to the code below.
inline double_constant_wrapper::double_constant_wrapper(double r)
{
   r_=r;
   if (r<0.0)
     throw exception("number cannot be <0");

}
the complier allocated the memory for the para "r_",and the exception
doesn't affect the value of the member.

it's my opinion.

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