given == for?

[b4swine]

Is there any difference at all between given(...) and foreach(...) in 5.010? Or is it there just so that we slowly get more comfortable with Perl 6 syntax?

OOPS: Now I understand. given(...) considers a list as an array reference, and never loops. Is that right?

[moritz]

You're correct. given aliases its argument to a lexicalized $_, but does no looping.

[LanX]

Hi, maybe you're interested in this old discussion "Understanding the benefit of Given/When ..." comparing given/when with for/next.

[b4swine]

Thanks. That is a much more detailed thread, and interesting. Perhaps you could post a summary of the conclusions reached by the end of that thread.

[LanX]

Well, the first post already has the conclusions formulated as rhetoric question.

Plz take a close look at the code examples, too!

Most of the following thread is about underlying design decisions and mechanisms of the smart match operator (which is implicitly used in when).

[dave_the_m]

for makes $_ an alias, given doesn't:

$ perl5120 -wE'my $x=1; given ($x) { $_ = 2 } say $x'
1
$ perl5120 -wE'my $x=1; for ($x) { $_ = 2 } say $x'
2

Edit: For some reason I wrote when rather than given above. Now fixed.

Dave.

[JavaFan]

Besides looping, foreach allows assigning the topic to a variable (foreach my $foo (...)), C-style loops (foreach (my $i = 0; $i < ...; $i++)) and its use a statement modifier. Furthermore, you cannot use a continue block, next, last or redo with given.

At the moment, I can't think of anything given gives you that for/foreach doesn't.

[moritz]

At the moment, I can't think of anything given gives you that for/foreach doesn't.

Catching break.

If you nest a for-loop and a given, you can selectively escape them with last and break.

(OK, you can do that with labels too).

[JavaFan]

If you nest a for-loop and a given, you can selectively escape them with last and break.

(OK, you can do that with labels too).

At least last allows labels - break doesn't.