What is your favorite D feature?

[k-five via Digitalmars-d]

On Thursday, 22 June 2017 at 00:48:25 UTC, Seb wrote:
> Hi,
>
> I am currently trying to modernize the D code example roulette 
> on the dlang.org front page [1]. Hence, I would love to hear 
> about your favorite feature(s) in D.
> Ideas:
> - favorite language construct
> - favorite code sample
> - "only possible in D"
>
> Before you ask, yes - I want to add a couple of cool examples 
> to dlang.org (and yep the roulette rotation is currently broken 
> [2]).
>
> [1] 
> https://github.com/dlang/dlang.org/pulls?q=is%3Apr+is%3Aopen+label%3A%22Frontpage+example%22
> [2] https://github.com/dlang/dlang.org/pull/1757

On Thursday, 22 June 2017 at 00:48:25 UTC, Seb wrote:


Universal Function Call Syntax ( UFCS )

Sample code on my gitgub + screen-shot,

https://github.com/k-five/dren

main code: recursively renaming files based on Regexes

dirEntries( ".", ( args[ 4 ] == "-r" ? SpanMode.depth : 
SpanMode.shallow ), false )
	.filter!( file => !file.name.matchFirst( regex( args[ 1 ] ) 
).empty() )
	.filter!( file => ( args[ 3 ] == "-f" || args[ 3 ] == "-d"  ? ( 
args[ 3 ] == "-f" ? !file.isDir : !file.isFile ) : ( 
!file.isSymlink ) ) )
	.map!( file => file.name )
         .each!( ( string result ) => ( args[ 5 ] == "-y" ? 
rename( result, replaceFirst( result, regex( args[ 1 ] ), args[ 2 
] ) ) : writeln( "print: ",result, " >> ", replaceFirst( result, 
regex( args[ 1 ] ), "\033[1;32m" ~ args[ 2 ] ~ "\033[m" ) ) ) );