Re: reddit.com: first Chapter of TDPL available for free

2009-08-08 Thread Jarrett Billingsley 
On Sat, Aug 8, 2009 at 8:44 PM, Jos van Udenj...@nospam.nl wrote:
 Andrei Alexandrescu wrote:


 http://www.reddit.com/r/programming/comments/975ng/diving_into_the_d_programming_language_tdpl/

 (Don't tell anyone, but I plan to rewrite it.)

 Andrei

 Is this supposed to compile? I keep getting error messages.

 import std.stdio, std.string;

 void main() {
   uint[string] dic;
   foreach (line; stdin.byLine) {
      // Break sentence into words
      string[] words = split(strip(line));
      // Add each word in the sentence to the vocabulary
      foreach (word; words) {
         if (word in dic) continue; // nothing to do
         uint newID = dic.length;
         dic[word] = newID;
         writeln(newID, '\t', word);
      }
   }
 }


 test.d(7): Error: function std.string.split (immutable(char)[] s) does not
 match parameter types (char[])
 test.d(7): Error: cannot implicitly convert expression (strip(line)) of type
 char[] to immutable(char)[]
 test.d(7): Error: expected 2 function arguments, not 1


 I've changed the code to:

 import std.stdio;
 import std.string;

 void main() {

    uint[string] dic;
    foreach (line; stdin.byLine) {
        string[] words = split(strip!(string)(line));
        foreach (word; words) {
            if (word in dic) {
                continue;
            }
            uint newID = dic.length;
            dic[word] = newID;
            writeln(newID, '\t', word);
        }
    }
 }

 but I still get an error...

 test.d(12): Error: cannot implicitly convert expression (line) of type
 char[] to immutable(char)[]


It's not documented, but the .byLine method returns char[], not
immutable(char)[] (string).  This is because the 'line' variable is
reused on each new line of the input, to improve speed.  I think to
solved this, you should use:

auto words = split(strip(line.idup));

The .idup creates a new duplicate of the line that is immutable.

Now, why split() doesn't take a const(char)[] is beyond me..

Re: reddit.com: first Chapter of TDPL available for free

2009-08-08 Thread Jos van Uden 

Jarrett Billingsley wrote:

On Sat, Aug 8, 2009 at 8:44 PM, Jos van Udenj...@nospam.nl wrote:

Andrei Alexandrescu wrote:


http://www.reddit.com/r/programming/comments/975ng/diving_into_the_d_programming_language_tdpl/

(Don't tell anyone, but I plan to rewrite it.)

Andrei

Is this supposed to compile? I keep getting error messages.

import std.stdio, std.string;

void main() {
  uint[string] dic;
  foreach (line; stdin.byLine) {
 // Break sentence into words
 string[] words = split(strip(line));
 // Add each word in the sentence to the vocabulary
 foreach (word; words) {
if (word in dic) continue; // nothing to do
uint newID = dic.length;
dic[word] = newID;
writeln(newID, '\t', word);
 }
  }
}


test.d(7): Error: function std.string.split (immutable(char)[] s) does not
match parameter types (char[])
test.d(7): Error: cannot implicitly convert expression (strip(line)) of type
char[] to immutable(char)[]
test.d(7): Error: expected 2 function arguments, not 1


I've changed the code to:

import std.stdio;
import std.string;

void main() {

   uint[string] dic;
   foreach (line; stdin.byLine) {
   string[] words = split(strip!(string)(line));
   foreach (word; words) {
   if (word in dic) {
   continue;
   }
   uint newID = dic.length;
   dic[word] = newID;
   writeln(newID, '\t', word);
   }
   }
}

but I still get an error...

test.d(12): Error: cannot implicitly convert expression (line) of type
char[] to immutable(char)[]



It's not documented, but the .byLine method returns char[], not
immutable(char)[] (string).  This is because the 'line' variable is
reused on each new line of the input, to improve speed.  I think to
solved this, you should use:

auto words = split(strip(line.idup));

The .idup creates a new duplicate of the line that is immutable.

Now, why split() doesn't take a const(char)[] is beyond me..


Yep, that solves it, in both cases.

Jos