Re^2: Building List::Compare objects for unknown numbers of objects

Great - thanks for your help. I read the documentation quite carefully and was aware that you need to pass array references. But to someone of my background (biologist with a little self-taught Perl) it wasn't obvious to me that the '->new' method would interpret the @A to provide the array references to generate the object. I suppose I thought it would need something to tell it to look at the contents of @A instead of @A itself. Instead I thought that perl would interpolate the "$var1" first and then the resulting text would be correctly interpreted by the method. I obviously lack some basic understanding here...

Comment on Re^2: Building List::Compare objects for unknown numbers of objects

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Re^3: Building List::Compare objects for unknown numbers of objects by hippo (Archbishop) on Nov 21, 2018 at 14:13 UTC
I suppose I thought it would need something to tell it to look at the contents of @A instead of @A itself. Quite the reverse. You have to work at it in order to refer to the array rather than its contents. Consider these two separate lines from the code above: `print "intesection is @intersection\n";` [download] Here, despite being contained within a string, it is the contents of the array which are printed, not the array as a container. `my @A = (\@S1, \@S2, \@S3);` [download] Whereas here, we have had to create references to each of the S arrays so that they are not flattened when assigning to `@A`. Further reading: Arrays: A Tutorial/Reference, perldata, perlref	[reply] [d/l] [select]

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Re^3: Building List::Compare objects for unknown numbers of objects
by hippo (Archbishop) on Nov 21, 2018 at 14:13 UTC

I suppose I thought it would need something to tell it to look at the contents of @A instead of @A itself.

Quite the reverse. You have to work at it in order to refer to the array rather than its contents. Consider these two separate lines from the code above:

print "intesection is @intersection\n";
[download]

Here, despite being contained within a string, it is the contents of the array which are printed, not the array as a container.

my @A = (\@S1, \@S2, \@S3);
[download]

Whereas here, we have had to create references to each of the S arrays so that they are not flattened when assigning to @A.

Further reading: Arrays: A Tutorial/Reference, perldata, perlref

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