Re^2: Can't understand function returning undefs

Here is what drives me crazy:

if(undef, undef){
    print "OK1\n";
}

if( (undef, undef) ){
    print "OK2\n";
}

my @a = (undef, undef);
if(@a){
    print "OK3\n";
}
[download]

This prints OK3. According to the above, it should also print OK2 because (undef, undef) is a list of two elements that evaluates to 2 in scalar context. Still, it doesn't.

rg0now

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Re^3: Can't understand function returning undefs by JavaFan (Canon) on Sep 24, 2010 at 21:57 UTC
There are no lists in scalar context! It's SCALAR context. What you have in `if (undef, undef) { # An extra set of parens doesn't matter. print "OK1\n"; }` [download] is the comma operator in scalar context. Which evaluates its LHS, throws it away, then returns its RHS. Which is `undef`, and hence false. According to the above If with "above" you mean the post you're replying to, you notice I talk about list ASSIGNMENT. Not lists. Nor arrays.	[reply] [d/l] [select]
Re^4: Can't understand function returning undefs by ikegami (Patriarch) on Sep 24, 2010 at 22:03 UTC
is the comma operator in scalar context. It's funny how you say something doesn't exist right before you say the thing that doesn't exist is what he has. (Sure, you used a different name for it.)	[reply] [d/l]