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Re^2: Perl6 dot syntax (for methods?)

by Ven'Tatsu (Deacon)
on Feb 28, 2005 at 16:26 UTC ( #435102=note: print w/replies, xml ) Need Help??


in reply to Re: Perl6 dot syntax (for methods?)
in thread Perl6 dot syntax (for methods?)

This is not unlike just saying $x although they are not interchangable (don't as my why, I am still trying to grok details like this myself).

There are two differences that I can see between *$x and $x. The first is parameter checking:

sub fooprintf (*$fmt, *@args) { ... } sub barprintf ($fmt, *@args) { ... } $foramt = '%5d %10s'; @data = (16, "baz"); @both = ('%5d %10s', 16, "baz"); fooprintf($format, @data); #this works fooprintf(@both); #so will this barprintf($format, @data); #this works barprintf(@both); #this won't work barprintf(*@both); #but this will

fooprintf will take any LIST of arguments and will just trust you the the first item in the (flatened) list is a scalar, while barprintf will force you to give it a scalar as it's first argument, or force you to flaten any arguments you pass it your self. In some cases this could catch at compile time errors that Perl5 would not have caught until runtime. (can you see the uncaught error in printf $format @data or the reverse printf $filehandle, @both?)

The other issue is context, ponder these:

fooprintf(localtime); #localtime is called in array context barprintf(localtime); #localtime is called in scalar context

If your intent was to print out the current seconds then the fooprintf will work, if however you were looking for the strigified representation of the current time barprintf is will likely be closer to what you expected.

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Re^3: Perl6 dot syntax (for methods?)
by Mugatu (Monk) on Feb 28, 2005 at 23:42 UTC
    In Perl5, the contexts are called scalar and list, despite the fact that wantarray is misnamed. Is this going to change in Perl6? Will there be an array and a list context that are separate and distinct? Or was "array context" simply a slip-up?

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