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From: Junio C Hamano <junkio@cox•net>
To: merlyn@stonehenge•com (Randal L. Schwartz)
Cc: Jakub Narebski <jnareb@gmail•com>, git@vger•kernel.org
Subject: Re: [PATCH] gitweb:  Make git_get_refs_list do work of  git_get_references
Date: Sat, 16 Sep 2006 19:12:27 -0700	[thread overview]
Message-ID: <7vejub8cms.fsf@assigned-by-dhcp.cox.net> (raw)
In-Reply-To: <864pv7tgmx.fsf@blue.stonehenge.com> (Randal L. Schwartz's message of "16 Sep 2006 18:40:22 -0700")

merlyn@stonehenge•com (Randal L. Schwartz) writes:

>>>>>> "Junio" == Junio C Hamano <junkio@cox•net> writes:
>
> Junio> Jakub Narebski <jnareb@gmail•com> writes:
>>> Make git_get_refs_list do also work of git_get_references, to avoid
>>> calling git-peek-remote twice. It now returns either list of refs as
>>> before in scalar context, or references hash and list of refs in list
>>> context.
>
> Junio> I do not think we want to have too many functions that return
> Junio> different things depending on contexts.  Forcing callers to
> Junio> remember what the function does in which context is bad.
>
> That's even an inaccurate description, so an expert in Perl (I've
> known a few) would just scratch his head.
>
> You cannot ever ever return a list in a scalar context.  Ever.  Never ever.

That much I think I know.

The code I was complaining about tries to do something like
this:

	sub that_sub {
        	...
                return wantarray ? (\@bar, \%foo) : \@bar;
	}

and it is not done for optimization purposes (i.e. "if the
caller only wants one and we are returning \@bar then we do not
have to compute \%foo which is a big win" is not why it does
this wantarray business).

So the callers when interested in the sequence of things in 'bar'
typically say:

	my $the_list = that_sub(...);
        for (@$the_list) {
        	...
	}

while other callers say:

	my ($the_hash, $the_list) = that_sub(...);
	... use %$the_hash and @$the_list as see fit ...

And I was saying that getting rid of the "return wantwarray ? :"
business and write the first class of callers like this

	my ($the_list) = that_sub(...);
        for (@$the_list) {
        	...
	}

would be much less confusing.

next prev parent reply	other threads:[~2006-09-17  2:12 UTC|newest]

Thread overview: 10+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2006-09-17  0:26 [PATCH] gitweb: Make git_get_refs_list do work of git_get_references Jakub Narebski
2006-09-17  0:37 ` [PATCH 1/2] gitweb: Always use git-peek-remote in git_get_references Jakub Narebski
2006-09-17  1:22 ` [PATCH] gitweb: Make git_get_refs_list do work of git_get_references Junio C Hamano
2006-09-17  1:40   ` Randal L. Schwartz
2006-09-17  2:12     ` Junio C Hamano [this message]
2006-09-17  2:17       ` Randal L. Schwartz
2006-09-17  2:29       ` Junio C Hamano
     [not found] ` <200609171057.56467.jnareb@gmail.com>
     [not found]   ` <7vfyeq6dn3.fsf@assigned-by-dhcp.cox.net>
2006-09-17 10:00     ` [PATCH 2/2 (take 2)] " Jakub Narebski
2006-09-17 10:02       ` Jakub Narebski
2006-09-17 10:06         ` Jakub Narebski

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