"TSa (Thomas Sandlaß)" skribis 2005-05-18 21:54 (+0200): > Juerd wrote: > >> my @b = [1,2,[3,4]]; > >> is([EMAIL PROTECTED], 1, 'Array length, nested [], outer []s'); > Isn't that a bit inconvenient? To get e.g. 2 out of @b > one has to write @b[0][1] while for $b a $b[1] suffices.
http://learn.perl.org/library/beginning_perl/ Parens and square brackets are very different things. The above is more commonly written as my @b = ([1,2,[3,4]); Having arrayrefs flatten in list context, or having [] to be able mean something other than constructing an arrayref, is a change that requires the very fundaments of Perl to change very heavily, beginning by eliminating lists entirely, and using only arrays. I believe I said it before, but I'll do it again: Perl is not Python. Just that the two languages are both powerful, and both begin with a P, and in some respects even syntactically look like eachother (hey, that's what we get for loving ASCII), doesn't mean any theory applicable to one automatically makes sense for the other. > And @x = @b maintains this superficial level of indirection? ARRAY = LIST is the syntax for assigning to an array. Note that the RHS is list context, not Array context. > Does @x = @b[] remove one level? How does that compare No. As far as I know, @b[] and @b are the synonymous. > my @b = (1,2,[3,4]); > is equivalent to > my $b = [1,2,[3,4]]; No, that's not equivalent. $b contains a reference to an array, while @b itself is an array. Hoping the box diagram worked the last time, I'll try again: +-- @b +-- $b (this array has no name; | | it is "anonymous") V V +----------+ +------------+ +----------+ | elements | | reference ----> | elements | +----------+ |------------+ +----------+ ARRAY SCALAR ARRAY > which in turn is equivalent to > my $b = (1,2,[3,4]); That is only because the comma operator is in scalar context. The parens here merely GROUP, for precedence. my $b = eval "1,2,[3,4]" would be exactly the same. Just to show you the parens are NOT constructors of the list. > $b = @b No, that assigns a *reference to $b* to @b, without any copying of elements. > Am I insane? No, you just STILL can't cope with Perl's notion of names, containers and values, and you don't realise that () and [] are not related, more specifically: that () has absolutely nothing to do with arrays or lists. These are mistakes many Perl 5 beginners make, especially those coming from Python. Juerd -- http://convolution.nl/maak_juerd_blij.html http://convolution.nl/make_juerd_happy.html http://convolution.nl/gajigu_juerd_n.html
