RE: subroutine or subroutine
Janek:
Thank you for explaining the difference between calling
subroutines with vs. without the ampersand.
I'm glad I'm on the beginners list.
Sincerely,
Kevin Christopher
-- Original Message --
From: Camilo Gonzalez [EMAIL PROTECTED]
Date: Thu, 6 Jun 2002 08:23:33 -0500
Janek,
Wouldn't it print:
foo:
foo:A B C
Also, I believe that you must declare the subroutine before you
are allowed
to reference it without the . Am I right about that?
-Original Message-
From: Janek Schleicher [mailto:[EMAIL PROTECTED]]
Sent: Wednesday, June 05, 2002 5:10 AM
To: [EMAIL PROTECTED]
Subject: Re: subroutine or subroutine
Kevin Christopher wrote at Wed, 05 Jun 2002 04:58:38 +0200:
Yes, you can call subroutines either way, with or without
the . The
only case when the
subroutine must be prefixed with an ampersand is, I believe,
when you're
assigning a reference
variable, eg:
$reference_x = \subroutine_y;
But that's another story.
Oh, I'm afraid that's not the truth :-)
subroutine without any arguments calls the subroutine with the
implicit @_
array,
while subroutine only calls subroutine() without any argument.
Look at this snippet:
@_ = qw(A B C);
print 'foo:'; foo; print \n;
print 'foo:'; foo; print \n;
sub foo {
print @_;
}
It prints:
foo:
foo:ABC
Greetings,
Janek
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RE: subroutine or subroutine
Janek,
Wouldn't it print:
foo:
foo:A B C
Also, I believe that you must declare the subroutine before you are allowed
to reference it without the . Am I right about that?
-Original Message-
From: Janek Schleicher [mailto:[EMAIL PROTECTED]]
Sent: Wednesday, June 05, 2002 5:10 AM
To: [EMAIL PROTECTED]
Subject: Re: subroutine or subroutine
Kevin Christopher wrote at Wed, 05 Jun 2002 04:58:38 +0200:
Yes, you can call subroutines either way, with or without the . The
only case when the
subroutine must be prefixed with an ampersand is, I believe, when you're
assigning a reference
variable, eg:
$reference_x = \subroutine_y;
But that's another story.
Oh, I'm afraid that's not the truth :-)
subroutine without any arguments calls the subroutine with the implicit @_
array,
while subroutine only calls subroutine() without any argument.
Look at this snippet:
@_ = qw(A B C);
print 'foo:'; foo; print \n;
print 'foo:'; foo; print \n;
sub foo {
print @_;
}
It prints:
foo:
foo:ABC
Greetings,
Janek
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RE: subroutine or subroutine
Bob, Since this is a list for newbies, can you please be a bit more specific why you are opposed to those things you list. I'm quite fond of using the foo or foo(args) calling styles. Is this just a personal preference? -Original Message- From: Bob Showalter [mailto:[EMAIL PROTECTED]] Sent: Wednesday, June 05, 2002 8:30 AM To: 'Octavian Rasnita'; [EMAIL PROTECTED] Subject: RE: subroutine or subroutine -Original Message- From: Octavian Rasnita [mailto:[EMAIL PROTECTED]] Sent: Tuesday, June 04, 2002 2:06 PM To: [EMAIL PROTECTED] Subject: subroutine or subroutine Hi all, I've seen some subroutines are ran without the sign in front of the subroutine name, like: subroutine_name; instead of subroutine_name; Is it the same thing or there is a difference? Janek gave you the difference, and it's fully documented in perldoc perlsub. Note that the first is not allowed under use strict unless the sub has been declared or defined above the usage, or imported. Here are my recommendations for new code (others may want to debate these): 1. Always use strict; 2. Don't use prototypes. 3. Don't use the foo or foo(args) calling styles. 4. To call a sub with no arguments, use an empty set of parens: foo() (Exception: method calls can leave off the parens, e.g: $sth-execute; since there is no ambiguity with a method call). -- To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED] -- To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED]
RE: subroutine or subroutine
No, the subroutinue body can occur before or after the invokation point with
or without the .
joel
-Original Message-
From: Camilo Gonzalez [mailto:[EMAIL PROTECTED]]
Sent: 06 June 2002 14:24
To: 'Janek Schleicher'; [EMAIL PROTECTED]
Subject: RE: subroutine or subroutine
Janek,
Wouldn't it print:
foo:
foo:A B C
Also, I believe that you must declare the subroutine before you are allowed
to reference it without the . Am I right about that?
-Original Message-
From: Janek Schleicher [mailto:[EMAIL PROTECTED]]
Sent: Wednesday, June 05, 2002 5:10 AM
To: [EMAIL PROTECTED]
Subject: Re: subroutine or subroutine
Kevin Christopher wrote at Wed, 05 Jun 2002 04:58:38 +0200:
Yes, you can call subroutines either way, with or without the . The
only case when the
subroutine must be prefixed with an ampersand is, I believe, when you're
assigning a reference
variable, eg:
$reference_x = \subroutine_y;
But that's another story.
Oh, I'm afraid that's not the truth :-)
subroutine without any arguments calls the subroutine with the implicit @_
array,
while subroutine only calls subroutine() without any argument.
Look at this snippet:
@_ = qw(A B C);
print 'foo:'; foo; print \n;
print 'foo:'; foo; print \n;
sub foo {
print @_;
}
It prints:
foo:
foo:ABC
Greetings,
Janek
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Fwd: notBob clarifies the Bob was Re: subroutine or subroutine
Begin forwarded message:
From: drieux [EMAIL PROTECTED]
Date: Thu Jun 06, 2002 07:38:29 US/Pacific
To: begin begin [EMAIL PROTECTED]
Subject: notBob clarifies the Bob was Re: subroutine or subroutine
On Thursday, June 6, 2002, at 06:31 , Camilo Gonzalez wrote:
[..]
Since this is a list for newbies, can you please be a bit more specific
why
you are opposed to those things you list. I'm quite fond of using the
foo
or foo(args) calling styles. Is this just a personal preference?
[..]
Bob Said:
Here are my recommendations for new code (others may want to debate
these)
:
1. Always use strict;
2. Don't use prototypes.
3. Don't use the foo or foo(args) calling styles.
4. To call a sub with no arguments, use an empty set of
parens: foo() (Exception: method calls can leave
off the parens, e.g: $sth-execute; since there is
no ambiguity with a method call).
notBob says:
1) the 'use strict' pragma helps pop out things
like wacko ref cases as well as making sure
that you do not have any wacko sub situations
and will WHINE at you at compile time This
while ANNOYING at compile time helps impose good habits,
probably faster than making you stand at the chaulk board
writing
I will not write bad code x 1_000_000_000
to impress upon the impressionable that good form is elegant.
2) the 'prototype' approach gets harry and messy when you
start certain types of software development - it was an
interesting idea - but as you will note in the 3rd edition
of programming perl it is not recommended.
{ Nikola probably has sanity issues that he is resolving
with prototyping - but then again, most of us are all
sublimating one or more issues in perl... }
May I recommend Miss Happy's House of Dominitrix Delights
if you have unresolved bondage needs as a simpler and more
direct solution to prototyping perl functions.
{ I think 'use subs qw//;' is not as cool as it was either. }
/* do not let me prevent you from learning the hard way. */
3) the foo and foo(@arglist) models are 'old perl' - and it
was so much nicer once we were allowed to go with
foo();
so that the 'oldGuys' felt more at home that this was
a 'function' that was called with no args... Nothing like
that annoying typo HELL of
if ( $wombat foo(@arglist) )
which you had intended to have been the foo() bitwise
added with $wombat - but got the logical anded. OYE!
You find that one at Oh-Dark-Squat without a Whole Lot of
Mountain Dew and.
{ hey crayon heads - did your colour coded perl IDE help in this case? }
In short these are recommendations based upon life experience,
our life, our experience - you are free to go with the flow or
not - but if you see me 'weaving down the road' while walking,
just accept the fact that I do that to make it harder on the
amatuer snipers. If you see me running, all you need to
do is be in front of me.
ciao
drieux
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RE: subroutine or subroutine
Bob Showalter wrote at Wed, 05 Jun 2002 15:30:29 +0200:
3. Don't use the foo or foo(args) calling styles.
Allthough I would miss it a little bit.
I find the foo style useful when implementing a little polymorphic subroutine.
Example:
sub foo {
/NUMERIC/ _foo_numeric
or /WORD/ _foo_word
or otherwise _foo_crazy;
}
sub _foo_numeric {
print Numbers: @_\n;
}
sub _foo_word {
print Words: @_\n;
}
sub _foo_crazy {
print Crazy: @_\n;
}
foo(NUMERIC = (4,5,6));
foo(WORD= (x,y,z));
foo(BIGJ = (the greatest));
It's more practical than writing
_foo_numeric( @_ )
_foo_word ( @_ )
_foo_crazy ( @_ )
in the switch case. (In addition I reduce the redundances).
Allthough, there are better (and slower :-( )
ways to implement polymorphic in a real OO-style,
I often use the upper behaviour in CGI scripts.
Cheerio,
Janek
PS: I hope that won't become a religious dibute of using foo - style vs foo() style.
All I wanted was to declare that there are some really useful reasons for the foo
style.
I want to underline Bob in saying: Don't use the foo style without special reason.
Especially don't use it mixed with the foo() style.
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Re: subroutine or subroutine
Yes, you can call subroutines either way, with or without the . The only case when the subroutine must be prefixed with an ampersand is, I believe, when you're assigning a reference variable, eg: $reference_x = \subroutine_y; But that's another story. Kevin -- Original Message -- From: Octavian Rasnita [EMAIL PROTECTED] Date: Tue, 4 Jun 2002 21:06:19 +0300 Hi all, I've seen some subroutines are ran without the sign in front of the subroutine name, like: subroutine_name; instead of subroutine_name; Is it the same thing or there is a difference? Thank you. Teddy, [EMAIL PROTECTED] -- To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED] -- To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED]
Re: subroutine or subroutine
Kevin Christopher wrote at Wed, 05 Jun 2002 04:58:38 +0200:
Yes, you can call subroutines either way, with or without the . The only case
when the
subroutine must be prefixed with an ampersand is, I believe, when you're assigning a
reference
variable, eg:
$reference_x = \subroutine_y;
But that's another story.
Oh, I'm afraid that's not the truth :-)
subroutine without any arguments calls the subroutine with the implicit @_ array,
while subroutine only calls subroutine() without any argument.
Look at this snippet:
@_ = qw(A B C);
print 'foo:'; foo; print \n;
print 'foo:'; foo; print \n;
sub foo {
print @_;
}
It prints:
foo:
foo:ABC
Greetings,
Janek
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RE: subroutine or subroutine
-Original Message- From: Octavian Rasnita [mailto:[EMAIL PROTECTED]] Sent: Tuesday, June 04, 2002 2:06 PM To: [EMAIL PROTECTED] Subject: subroutine or subroutine Hi all, I've seen some subroutines are ran without the sign in front of the subroutine name, like: subroutine_name; instead of subroutine_name; Is it the same thing or there is a difference? Janek gave you the difference, and it's fully documented in perldoc perlsub. Note that the first is not allowed under use strict unless the sub has been declared or defined above the usage, or imported. Here are my recommendations for new code (others may want to debate these): 1. Always use strict; 2. Don't use prototypes. 3. Don't use the foo or foo(args) calling styles. 4. To call a sub with no arguments, use an empty set of parens: foo() (Exception: method calls can leave off the parens, e.g: $sth-execute; since there is no ambiguity with a method call). -- To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED]
RE: subroutine or subroutine
I'd suggest using prototypes if you are going to be passing more than 3 variable references, or 3 or more different types of varible references. This is for your own sanity. -Original Message- From: Bob Showalter [mailto:[EMAIL PROTECTED]] Sent: Wednesday, June 05, 2002 9:30 AM To: 'Octavian Rasnita'; [EMAIL PROTECTED] Subject: RE: subroutine or subroutine Here are my recommendations for new code (others may want to debate these): 1. Always use strict; 2. Don't use prototypes. 3. Don't use the foo or foo(args) calling styles. 4. To call a sub with no arguments, use an empty set of parens: foo() (Exception: method calls can leave off the parens, e.g: $sth-execute; since there is no ambiguity with a method call). -- To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED] The views and opinions expressed in this email message are the sender's own, and do not necessarily represent the views and opinions of Summit Systems Inc. -- To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED]
