Re: Did I get what I expected (an array)?

Yes, you explained what you want. It's also clear you lack some fundamental knowledge about Perl. You need to make yourself more familiar with the concept context. A subroutine will return a list if and only if it was called in list context. A subroutine will return a scalar if and only if it was called in scalar context. A subroutine will return nothing if and only if it was called in void context. The crucial point is that it is the context that determines whether the subroutine returns a list or a scalar - not the subroutine.

Furthermore, parenthesis do not create lists (except in some very specific syntax constructs). Parenthesis are used for grouping.

    return $this;
    return ($this);
    return (($this));
    return ((($this)));
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all mean the same. The do not differ just like there is no difference between:

    3 + 4;
    (3 + 4);
    (3) + (4);
    ((3) + (4));
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As for

    return @x;
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that will return the number of elements of @x in scalar context, and a list consisting of the elements of @x in list context. Perl will never return an array. You can check for yourself:

    my @x = qw /foo bar baz/;
    sub my_func {return @x};
    (my_func) [1] .= "hello";
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This gives a compile error:

    Can't modify list slice in concatenation (.) or string
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Note that it says "list slice". A list, not an array.

Abigail

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Re: Re: Did I get what I expected (an array)? by bronto (Priest) on Jul 17, 2002 at 08:21 UTC
First of all: thanks Abigail! Second: sorry for posting as Anonymous Monk, unfortunately Konqueror had me and broke my authentication. If I can recover that node by any mean I'll be thankful Now back to Perl. Actually I am guilty, yes, but not of the sin you are accusing me `:-)`. I didn't get, and probabily I still have to meditate about, the difference between lists and arrays. But I know what "context" means. Otherwise, I wouldn't write: `$test = test() ; @test = test() ; print $test == scalar(@test)? "Yepa!\n" : "Nope!\n" ;` [download] The idea under that snippet was: retrieve in scalar context and in list context; if `$test` matches `scalar @test` then surely we `return @x`. About the `return` thing, you got a point: I forgot the golden rule if it seems a function, it is a function; moreover, I remembered `return LIST` from the docs, but it's `return EXPR`. I'm a sinner `;)` Last but not least, for everybody telling me about `wantarray`: you completely missed the point, but it probabily was my english's fault. I didn't tell I was looking for a way to write a better `return` statement. Instead, I was trying to test a return value of a sub/method, whoever wrote it. I can't enforce `wantarray` usage on people that is subclassing a class of mine. Anyway, another lesson learnt. Thanks to everybody Ciao! `--bronto` # Another Perl edition of a song: # The End, by The Beatles END { $you->take($love) eq $you->made($love) ; }	[reply] [d/l] [select]

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Re: Re: Did I get what I expected (an array)?
by bronto (Priest) on Jul 17, 2002 at 08:21 UTC

First of all: thanks Abigail!

Second: sorry for posting as Anonymous Monk, unfortunately Konqueror had me and broke my authentication. If I can recover that node by any mean I'll be thankful

Now back to Perl. Actually I am guilty, yes, but not of the sin you are accusing me :-). I didn't get, and probabily I still have to meditate about, the difference between lists and arrays. But I know what "context" means.

Otherwise, I wouldn't write:

$test = test() ;
@test = test() ;
print $test == scalar(@test)? "Yepa!\n" : "Nope!\n" ;
[download]

The idea under that snippet was: retrieve in scalar context and in list context; if $test matches scalar @test then surely we return @x.

About the return thing, you got a point: I forgot the golden rule if it seems a function, it is a function; moreover, I remembered return LIST from the docs, but it's return EXPR. I'm a sinner ;)

Last but not least, for everybody telling me about wantarray: you completely missed the point, but it probabily was my english's fault. I didn't tell I was looking for a way to write a better return statement. Instead, I was trying to test a return value of a sub/method, whoever wrote it. I can't enforce wantarray usage on people that is subclassing a class of mine.

Anyway, another lesson learnt. Thanks to everybody

Ciao!
--bronto

# Another Perl edition of a song:
# The End, by The Beatles
END {
  $you->take($love) eq $you->made($love) ;
}

[reply]
[d/l]
[select]