Beefy Boxes and Bandwidth Generously Provided by pair Networks
There's more than one way to do things
 
PerlMonks  

Comment on

( #3333=superdoc: print w/ replies, xml ) Need Help??

Are you implying that array slice make lists and arrays don't?

Yes.

How do you reconcile that with the fact that both the array and the array slice perform exactly the same action in list context: they put their members on the stack. Either they both make a list or neither does.

Following that model, in: $r = ($a, $b) = 0..11 ; the right-hand assignment: ($a, $b) = 0..11 happens first, so we get ($a=0, $b=1), then that is assigned to $r.... leaving to one side whether ($a, $b) is or isn't a list (given that for the right-hand assignment there's List Context, and in the left-hand one Scalar Context).... since the result is $r=12, right-associativity doesn't appear to be the whole story.

I bolded the mistake. Just like the right-hand ** doesn't return 3 in 2**3**4, The right-hand assignment doesn't return ($a, $b) in $r = ($a, $b) = 0..11. A list assignment in scalar context returns the number of items it was given to assign. 12, in this case.

>perl -le"print( scalar( ($a, $b) = 0..11 ) );" 12

Just for a moment, let's consider integers and floats as two different sorts of value. Now, '%' is an integer operation -- one could say it has "Integer Context" -- and the floating point argument is implicitly coerced to an integer, suitable for the '%' operation. At least that is a common understanding of what happens.

There are two different sort of value. Three even.
NVs hold floats (which could technically be integers, but not relevant).
IVs hold machine signed integers.
UVs hold machine unsigned integers.

I wouldn't say it has integer context, because that would imply a parallel with scalar vs list context. Scalar and list context force operands to returns a scalar and a list respectively. Integer coercion doesn't force operands to returns an integer.

Let's look at an example. Given f() % 3, f() is executed in scalar context and in "integer context".

Scalar ContextInteger Coercion
The scalar context will force f() to return a scalar. The integer conversion doesn't force f() to return an integer.
f() is unable to return a list. f() is free to return undef, a string, a reference, a float, etc.
% never converts a list to a scalar. The conversion to integer is performed by %.
The scalar context is forced onto the operands before they are evaluated. The integer coercion is performed on the operands after they are evaluated.

Your argument relies on the premise of a parallel between scalar context and integer coercion, but it's very clear there isn't one. The premise is false, so the argument is moot.

This isn't relevant, but I thought you'd be interested in an additional difference: some operators (such |, & and ^) behave differently based on whether they're given a string or an integer. Some operators behave differently based on the length of the list they are given, but you won't find an operator that can accept both a scalar and a list.

Update: Formatting changes. Minor typo correction.


In reply to Re^5: If you believe in Lists in Scalar Context, Clap your Hands by ikegami
in thread If you believe in Lists in Scalar Context, Clap your Hands by oshalla

Title:
Use:  <p> text here (a paragraph) </p>
and:  <code> code here </code>
to format your post; it's "PerlMonks-approved HTML":



  • Posts are HTML formatted. Put <p> </p> tags around your paragraphs. Put <code> </code> tags around your code and data!
  • Read Where should I post X? if you're not absolutely sure you're posting in the right place.
  • Please read these before you post! —
  • Posts may use any of the Perl Monks Approved HTML tags:
    a, abbr, b, big, blockquote, br, caption, center, col, colgroup, dd, del, div, dl, dt, em, font, h1, h2, h3, h4, h5, h6, hr, i, ins, li, ol, p, pre, readmore, small, span, spoiler, strike, strong, sub, sup, table, tbody, td, tfoot, th, thead, tr, tt, u, ul, wbr
  • Outside of code tags, you may need to use entities for some characters:
            For:     Use:
    & &amp;
    < &lt;
    > &gt;
    [ &#91;
    ] &#93;
  • Link using PerlMonks shortcuts! What shortcuts can I use for linking?
  • See Writeup Formatting Tips and other pages linked from there for more info.
  • Log In?
    Username:
    Password:

    What's my password?
    Create A New User
    Chatterbox?
    and the web crawler heard nothing...

    How do I use this? | Other CB clients
    Other Users?
    Others musing on the Monastery: (11)
    As of 2014-07-31 16:17 GMT
    Sections?
    Information?
    Find Nodes?
    Leftovers?
      Voting Booth?

      My favorite superfluous repetitious redundant duplicative phrase is:









      Results (249 votes), past polls