"Continue" usage

[Chris Dollin]

Re: "Continue& quot; usage

Nick Keighley wrote:

is clearer. For a start it avoids an inverted test.
I don't write predicates with "not" in the name.

I don't think that's a fair criticism; I thought Richard's
`complexConditi onNotMatched` was a standin for whatever
expression was required, with the `Not` showing intent,
not the actual presence of a `Not` in the name.

So
I would have coded your original example as
>
while(n--){
if (!complexCondit ionMatched(n))
continue; /* not interested. Check the next if there is one. */
>
/*do processing of things we are interested in*/
}
>
there is some evidence (if forced to cite I'll try "The Psychology
of Computer Programming") that human beings (including computer
programnmers) prefer positive to negative logic.

I think there are subsequent studies in that direction, but I
don't have a cite to hand. One of my rantettes is against languages
that don't have an `unless`.

--
'It changed the future .. and it changed us.' /Babylon 5/

Hewlett-Packard Limited registered office: Cain Road, Bracknell,
registered no: 690597 England Berks RG12 1HN

[CBFalconer]

Re: "Continue& quot; usage

Chris Dollin wrote:

>

.... snip ...

>
I think there are subsequent studies in that direction, but I
don't have a cite to hand. One of my rantettes is against
languages that don't have an `unless`.

How about:

unless (x) if (y) z;
-->
if (!x && y) z; /* for C */

--
[mail]: Chuck F (cbfalconer at maineline dot net)
[page]: <http://cbfalconer.home .att.net>
Try the download section.

[Ben Pfaff]

Re: &quot;Continue& quot; usage

CBFalconer <cbfalconer@yah oo.comwrites:

How about:
>
unless (x) if (y) z;
-->
if (!x && y) z; /* for C */

I suppose one could
#define unless(conditio n) if (!(condition))
but I would not advocate it.
--
Ben Pfaff

http://benpfaff.org

[Richard Bos]

Re: &quot;Continue& quot; usage

Ben Pfaff <blp@cs.stanfor d.eduwrote:

CBFalconer <cbfalconer@yah oo.comwrites:
>

How about:

unless (x) if (y) z;
-->
if (!x && y) z; /* for C */

>
I suppose one could
#define unless(conditio n) if (!(condition))
but I would not advocate it.

In other words, if you want PERL, you know where to find it.
(A sentiment which I heartily endorse.)

Richard

[Chris Dollin]

Re: &quot;Continue& quot; usage

Ben Pfaff wrote:

CBFalconer <cbfalconer@yah oo.comwrites:
>

>How about:
>>
> unless (x) if (y) z;
>-->
> if (!x && y) z; /* for C */

>
I suppose one could
#define unless(conditio n) if (!(condition))
but I would not advocate it.

Much as I like `unless`, I would not advocate this either. Dinking
around with control-structure macros is, I believe, a good way to
confuse the other programmers who might be working on your code.

/Sometimes/ you get enough ROI for it to be worthwhile, when the
macro(s) hide enough details in the right kind of way. I'm willing
to pay the !() price of an unless-less C; but any imperative language
I design has an `unless` conditional (and an `until` loop).

--
'It changed the future .. and it changed us.' /Babylon 5/

Hewlett-Packard Limited Cain Road, Bracknell, registered no:
registered office: Berks RG12 1HN 690597 England

[Ben Pfaff]

Re: &quot;Continue& quot; usage

Chris Dollin <chris.dollin@h p.comwrites:

Much as I like `unless`, I would not advocate this either. Dinking
around with control-structure macros is, I believe, a good way to
confuse the other programmers who might be working on your code.
>
/Sometimes/ you get enough ROI for it to be worthwhile, when the
macro(s) hide enough details in the right kind of way.

My favorite example of a worthwhile control structure macro is a
macro for iterating through linked lists constructed in clever
ways, so that code like

for (node = list; node != NULL; node = node->next) {
struct data *d = container_of(no de, struct data, member);
...do something with d...
}

(or often much worse than that) can be condensed to something
like

struct data *d;
LIST_FOR_EACH (d, struct data, member, list) {
...do something with d...
}

which personally seems more readable.
--
char a[]="\n .CJacehknorstu" ;int putchar(int);in t main(void){unsi gned long b[]
={0x67dffdff,0x 9aa9aa6a,0xa77f fda9,0x7da6aa6a ,0xa67f6aaa,0xa a9aa9f6,0x11f6} ,*p
=b,i=24;for(;p+ =!*p;*p/=4)switch(0[p]&3)case 0:{return 0;for(p--;i--;i--)case+
2:{i++;if(i)bre ak;else default:continu e;if(0)case 1:putchar(a[i&15]);break;}}}

[Antoninus Twink]

Re: &quot;Continue& quot; usage

On 22 Sep 2008 at 21:48, CBFalconer wrote:

Simply use goto. Note that this has the significant advantage that a
short search of the code source shows you the destination.

More fantastic advice for the C newbie from CBF...