On Sat, Jul 11, 2009 at 22:02, Minimiscience<minimiscie...@gmail.com> wrote:
> I tried to find the answers to these in the Synopses, but I couldn't.  Plan
> B is to ask the mailing list.
>  - What does the "first" method/subroutine return when no elements of the
> list match?  Does it return the empty list?  Does the return value count as
> undefined/failure?

from http://perlcabal.org/syn/S32/Containers.html
    grep takes a list or array of values and returns a lazily evaluated list
    comprised of all of the values from the original list for which the $test
    smart-matches as true.
    first works exactly like grep but returns only the first matching value.

Since grep is defined as returning a list of matching elements and first is
defined as being the same as grep, I would say that it returns an empty list
if nothing matches.  The empty list is one of the false values.

>  - What type is the $buf argument to the IO::Readable::read method supposed
> to be?  Should it be a Buf, and, if so, does the size of the Buf's elements
> matter?  How would one indicate a desired element size when reading to an
> uninitialized Buf?  A similar question also applies to IO::Writeable::write.
>  (Also, "Writable" is misspelled.)

from http://perlcabal.org/syn/S32/IO.html#IO%3A%3AReadable

    It is important to realize that this is "raw" read. You're going to have
    plain octets stored in $buf, if this is actually encoded data, you're
    going to need to encode it later, or use "getc" or other
    IO::Readable::Encoded methods.

Given that it claims that $buf will will contain plain octets, $buf should
be a Buf8.

>  - How does one get/set the number/size of elements in a Buf object?

No idea, I am not certain it has been defined yet.

>  - Exactly what happens if & when a call to open() fails?  Is an exception
> thrown, and, if so, how does one catch it?

The open function does throw an exception, and you catch it with try:


use v6;

my $fh;
try {
        $fh = open "foo.txt";
        CATCH {
                say "oops, file doesn't exist"

say "made it";

>  - How does one declare multiple variables of the same type with a single
> "my" statement?  Is it "my Int ($x, $y);", "my(Int $x, Int $y);", or
> something else?  Are the parentheses still necessary when declaring more
> than one variable?  What about when initializing more than one variable?

At least currently, only

my Int $x;
my Int $y;


>  - Is there some sort of shortcut (e.g., of the form ".‽method") for calling
> a method on an object if the object is defined and returning undef if it is
> not defined?  I was hoping that ".?method" could do this, but it doesn't
> seem to (in Rakudo, at least).

Not a clue.

> Thank you in advance,
>        Minimiscience

Chas. Owens
The most important skill a programmer can have is the ability to read.

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