Re: Re: How does ~~ force string interpolation of code into scalar context?

Hmm, stacking unary operators. I hadn't considered that as even being a possibility except for things like $$ and \\ for multiple levels of referencing/dereferencing.

Thanks for pointing out a new idiom for me (which may not be all that necessary but is definately interesting to understand).

In the spirit of exploration I found that the following will also at least compile and force scalar context. Some of them will mangle return values though. ;)

sub context {
    print wantarray ? "List\n" : "Scalar\n";
}


my $string;

$string = "Test ${\~~context()} string";
$string = "Test ${\!!context()} string";
$string = "Test ${\+-+context()} string";
$string = "Test ${\-+-context()} string";
$string = "Test ${\&\&context()} string";
[download]

Thanks again...

Dave

"If I had my life to live over again, I'd be a plumber." -- Albert Einstein

Comment on Re: Re: How does ~~ force string interpolation of code into scalar context? Download Code

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Re: Re: Re: How does ~~ force string interpolation of code into scalar context? by sauoq (Abbot) on Oct 25, 2003 at 22:05 UTC
I found that the following will also at least compile and force scalar context. Some of them will mangle return values though. ;) Actually, of the four additional combinations you tried, only `-+-` would be at all useful. It avoids mangling integers and floats. The three others mangle everything.¹ Also, with 5.6.1 and 5.8.0 at least, using this will cause warnings about ambiguity unless warnings are explicitly disabled. Still, it may have some golf merit in being a short way to impose scalar context on functions that return floating point numbers. For strings or ints, though, I think `~~` is still preferable. For golf or obfuscation that is. Of course, `scalar()` is far better for "real" code. By the way, `-+-` might also be written as `- -`, the plus or space only being necessary to differentiate it from a decrement. 1. In fact, `&\&` will, I think, always fail under strict checking. -sauoq "My two cents aren't worth a dime.";	[reply]
Re: Re: Re: How does ~~ force string interpolation of code into scalar context? by TomDLux (Vicar) on Oct 27, 2003 at 00:54 UTC
I think these CAN be useful ... for decorative purposes ... `$arg1 = "arg1"; $arg2 = "arg2"; $arg3 = "arg3"; sub f1 { return "1"; } sub f2 { return "0"; } sub f3 { return "3"; } print "${\-+- f1( $arg1 )}"; print "${\+-+ f2( $arg2 )}"; print "${\-+- f3( $arg3 )}"; print "\n"` [download] isn't that far better than the undecorated print statements? ( Same f1(), f2(), f3(), $arg1, $arg2, $arg3. ) `print f1( $arg1 ); print f2( $arg2 ); print f3( $arg3 );` [download] And FAR superior to the boring and mundane: `print "103\n";` [download] -- `TTTATCGGTCGTTATATAGATGTTTGCA`	[reply] [d/l] [select]
Re: Re: Re: Re: How does ~~ force string interpolation of code into scalar context? by davido (Cardinal) on Oct 27, 2003 at 01:01 UTC
Far better indeed, as your "undecorated print statements" don't interpolate the function f1, f2 and f3; they just print the literal text `f1( ... )`. The "decorative" version executes f1() with $arg1 as its parameter. Of course neither approach is better than `print "@{[f1( $arg1 )]}";`, and that method is, itself, usually worse than `print f1( $arg1 );` (without unnecessary interpolation). Dave "If I had my life to live over again, I'd be a plumber." -- Albert Einstein	[reply] [d/l] [select]