[EMAIL PROTECTED] wrote:
>
> Here's an excerpt about the & from orielly and what the heck does it means:
>
> "...If a subroutine is called using the & form, the argument list is
> optional. if ommitted, no @_ array is setup for the routine; the @_ array
> at the time of the call is visible to subroutine instead."
>
> So, is there a better or worse? both ways works for me. I just started
> going back and putting the & onto the sub ;) I don't like it the & but I
> thought that you need it.
No you don't need it and you shouldn't use it unless you do need it. And if
you don't know whether you need it or not then you probably don't need it.
perldoc perlsub
[snip]
A subroutine may be called using an explicit `&' prefix.
The `&' is optional in modern Perl, as are parentheses if
the subroutine has been predeclared. The `&' is not
optional when just naming the subroutine, such as when
it's used as an argument to defined() or undef(). Nor is
it optional when you want to do an indirect subroutine
call with a subroutine name or reference using the `&$sub
ref()' or `&{$subref}()' constructs, although the `$sub
ref->()' notation solves that problem. See the perlref
manpage for more about all that.
Subroutines may be called recursively. If a subroutine is
called using the `&' form, the argument list is optional,
and if omitted, no [EMAIL PROTECTED]' array is set up for the subrou
tine: the [EMAIL PROTECTED]' array at the time of the call is visible to
subroutine instead. This is an efficiency mechanism that
new users may wish to avoid.
&foo(1,2,3); # pass three arguments
foo(1,2,3); # the same
foo(); # pass a null list
&foo(); # the same
&foo; # foo() get current args, like foo(@_) !!
foo; # like foo() IFF sub foo predeclared, else "foo"
Not only does the `&' form make the argument list
optional, it also disables any prototype checking on argu
ments you do provide. This is partly for historical rea
sons, and partly for having a convenient way to cheat if
you know what you're doing. See the Prototypes manpage
below.
[snip]
Constant Functions
Functions with a prototype of `()' are potential candi
dates for inlining. If the result after optimization and
constant folding is either a constant or a lexically-
scoped scalar which has no other references, then it will
be used in place of function calls made without `&'.
Calls made using `&' are never inlined. (See constant.pm
for an easy way to declare most constants.)
John
--
use Perl;
program
fulfillment
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