Paranoid about style/elegance and function size, please quell

[kanze@gabi-soft.fr]

Re: Paranoid about style/elegance and function size, please quell

brangdon@cix.co .uk (Dave Harris) wrote in message
news:<memo.2003 0702204926.3391 1D@brangdon.mad asafish.com>...[color=blue]
> E.Robert.Tisdal e@jpl.nasa.gov (E. Robert Tisdale) wrote (abridged):[color=green]
> > Procedural programs are difficult to analyze and practically
> > impossible to prove correct. You should avoid procedure calls (and
> > assignment statements) whenever possible.[/color][/color]
[color=blue]
> Right. And you should make sure no-one confuses a procedure with a
> function. One way to achieve that is to make sure functions never have
> side effects and procedures never return results.[/color]

So what do you do with rand()? (I like the rule, but there are
exceptions.)

--
James Kanze GABI Software
mailto:kanze@ga bi-soft.fr
Conseils en informatique orientée objet/

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Datenverarbeitu ng
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[Dave Harris]

Re: Paranoid about style/elegance and function size, please quell

kanze@gabi-soft.fr () wrote (abridged):[color=blue][color=green]
> > Right. And you should make sure no-one confuses a procedure with
> > a function. One way to achieve that is to make sure functions
> > never have side effects and procedures never return results.[/color]
>
> So what do you do with rand()?[/color]

Rand ought to be an object anyway:

class {
int state; // or whatever
public:
void srand( int seed );
void advance();
int current() const;
// int next() const { advance(); return current(); }
};

[color=blue]
> (I like the rule, but there are exceptions.)[/color]

I agree there are exceptions. Another possible exception is having a
procedure return information about whether it succeeded.

These can be eliminated, of course, and some people say they always
should be, but I don't take that extreme view. The circumlocutions
sometimes have drawbacks which are worse than the problem they
solve.

-- Dave Harris, Nottingham, UK

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[Francis Glassborow]

Re: Paranoid about style/elegance and function size, please quell

In message <3F048BDA.30403 06@jpl.nasa.gov >, E. Robert Tisdale
<E.Robert.Tisda le@jpl.nasa.gov > writes[color=blue]
>Francis Glassborow wrote:
>[color=green]
>> And you were responding to Mr. Tisdale's rewriting of what I had written.[/color]
>
>Your function
>
> void foo(void){
> std::cout << std::clock();
> }
>
>modifies a global variable -- cout.[/color]

So? being a global it is available for anyone to check. Indeed if they
are really paranoid they can switch on exception behaviour for streams.


--
ACCU Spring Conference 2003 April 2-5
The Conference you should not have missed
ACCU Spring Conference 2004 Late April
Francis Glassborow ACCU


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[Francis Glassborow]

Re: Paranoid about style/elegance and function size, please quell

In message <l1llvepkg3.fsf @budvar.future-i.net>, Ed Avis
<ed@membled.com > writes[color=blue]
>I am just thinking of a relatively high-level interface such as
>
> class Screen {
> XXX display(Graphic );
> };
>
>XXX could be void or it could be Screen&, returning *this. The latter
>style would let you chain display() calls, if you are so inclined.[/color]

And if you read my original guideline it said something that included
that possibility. Tisdale may have taken us down this path but he was
disagreeing with a guideline that most seem to approve of. I wasn't the
OP but my guidelines were a response to his post. Tisdale claimed that
the guideline was a bad one. I have seen nothing to change my mind.

--
ACCU Spring Conference 2003 April 2-5
The Conference you should not have missed
ACCU Spring Conference 2004 Late April
Francis Glassborow ACCU


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[E. Robert Tisdale]

Re: Paranoid about style/elegance and function size, please quell

James Kanze:
[color=blue]
> Dave Harris) wrote:
>[color=green]
>>And you should make sure no-one confuses a procedure with a function.
>>One way to achieve that is to make sure that functions
>> never have side effects and procedures never return results.[/color]
>
> So what do you do with rand()?
> (I like the rule, but there are exceptions.)[/color]

The rand() function was a *bad* idea for a number of different reasons.
It should be replace with a Uniform Random Number Generator

class URNG {
private:
// state representation
public:
// operators
int operator()(void );
// constructors
URNG(unsigned int seed);
};

int main(int argc, char* argv[]) {
URNG rand(0);
// use rand()
return 0;
}


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[llewelly]

Re: Paranoid about style/elegance and function size, please quell

"E. Robert Tisdale" <E.Robert.Tisda le@jpl.nasa.gov > writes:
[color=blue]
> James Kanze:
>[color=green]
>> Dave Harris) wrote:
>>[color=darkred]
>>>And you should make sure no-one confuses a procedure with a function.
>>>One way to achieve that is to make sure that functions
>>> never have side effects and procedures never return results.[/color]
>>
>> So what do you do with rand()?
>> (I like the rule, but there are exceptions.)[/color]
>
> The rand() function was a *bad* idea for a number of different[/color]
reasons.[color=blue]
> It should be replace with a Uniform Random Number Generator
>
> class URNG {[/color]

Yes, however, let's please not give it a name which looks like a cross
between a macro and punch to the gut. Anyway, boost has some
rather nice random number generators.
[color=blue]
> private:
> // state representation
> public:
> // operators
> int operator()(void );
> // constructors
> URNG(unsigned int seed);
> };
>
> int main(int argc, char* argv[]) {
> URNG rand(0);
> // use rand()
> return 0;
> }[/color]
[snip]

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