Scriptometer

[Tomek Sowiński]

bearophile napisał(a):

>> Nice page. I submitted some "scripts" so D will be featured on it.
> You may show them here too.

Good idea. I must say it was fun writing "scripts" in D. They could use  
community sandblasting before publishing. Remember, the aim is to write  
the smallest program possible, so optimize character count (contiguous  
whitespaces count as 1).

smallest - the smallest running program doing nothing:
void main(){}

hello world - print a simple string on stdout:
import std.stdio;
void main(){writeln("Hello World");}

argv - access command line parameters (no segmentation fault accepted, nor  
silent exception, so some languages must explicitly check the presence of  
the argument):
import std.stdio;
void main(string[] a){if(a.length>1)writeln(a[1]);}

env - access environment variable:
import std.stdio,std.process;
void main(){writeln(getenv("HOME"));}

test file exists - return exit code error (non zero) if a file does not  
exist:
import std.file;
int main(){return !exists("/etc/mtab");}

test file readable - return exit code error (non zero) if a file is not  
readable:
import std.stdio;
void main(){File("/etc/mtab");}

formatting - print integers in a simple formatted string:
import std.stdio;
void main(){int a=1,b=2;writefln("%s + %s = %s",a,b,a+b);}

system - call an external program and check the return value:
import std.stdio,std.process;
void main(){if(system("false")) stderr.writeln("false failed");  
writeln("done");}

sed in place - remove #-comments from a file (modifying the file, i.e. in  
place):
import std.file,std.regex;
void main(string[] a){a[1].write(a[1].readText().replace(regex("#.*",  
"g"), ""));}

compile what must be - find and compile .c files into .o when the .o is  
old or absent:
import std.stdio,std.file,std.process;
void main(){
     foreach(c;listdir("","*.c")){
         auto o=c[0..$-1]~'o';
         if(lastModified(o,0)<lastModified(c)) {
             writefln("compiling %s to %s",c,o);
             system("gcc -c -o '"~c~"' '"~o~"'");
         }
     }
}

grep - grep with -F -i -h handling, usage, grep'ing many files:
import std.stdio,std.array,std.regex;
int main(string[] a){
     auto o=["-h":0,"-F":0,"-i":0];
     while(!(a=a[1..$]).empty) {
         if(auto b=a[0] in o) *b=1;
         else break;
     }
     if(!a.length||o["-h"]){
         writeln("usage: grep [-F] [-i] regexp [files...]");
         return 1;
     }
     auto e=o["-F"]?a[0].replace(regex(r"\W","g"),r"\$&"):a[0];
     foreach(f;a[1..$])
         foreach(l;File(f).byLine())
             if(!l.match(regex(e,o["-i"]?"i":"")).empty)
                 writeln(f,':',l);
     return 0;
}

-- 
Tomek