Re: [Boston.pm] catenation of undef with string, 2 cases

> On Nov 9, 2016, at 12:49 PM, Mike Small <[email protected]> wrote:
> 
> 
> #!/usr/pkg/bin/perl
> use warnings;
> 
> my $a;
> $a .= '70';
> my $b;
> $b = 42 . $b;
> print "$a, $b\n";
> 
> 
> With the script above I get an uninitialized value warning from perl
> 5.24 for the second concatenation but not the first. Is there a story
> behind this? Something to do with the first case being something you'd
> likely want to do without whinging from the interpreter?

Interestingly, if you swap the order of the second concatenation, you don’t get the warning, which makes it consistent.

I don’t know if this is the reason, but here’s a place this would be somewhat useful:

	...
	my $out;
	foreach my $k (sort keys %h) {
		$out .= “$k: $h{$k}\n”;
	}
	...

otherwise, you have to start with:

	my $out = ‘’;

(admittedly, that’s how I always start this, but it’s interesting to note that I could leave out the assignment to ‘’.)

Ricky


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