• Lurker #5 <lnumber5 klassmaster.com> Jun 26 2007
• Kirk McDonald <kirklin.mcdonald gmail.com> Jun 26 2007
• Derek Parnell <derek nomail.afraid.org> Jun 26 2007
• Robert Fraser <fraserofthenight gmail.com> Jun 27 2007

Lurker #5 <lnumber5 klassmaster.com> writes:

One more thing... How can I call a method by name? I was looking at the
ClassInfo but I cant' find a way to call a method like this:

class Commands
{
  void command1() {}
  void command2() {}
  void command3() {}
}

Commands cmds = new Commands();
char[] cmd = readLine();
call(cmd, cmd);

Any ideas on how to implement this call() method?

Tnks

Kirk McDonald <kirklin.mcdonald gmail.com> writes:

Lurker #5 wrote:
 One more thing... How can I call a method by name? I was looking at the
ClassInfo but I cant' find a way to call a method like this:
 
 class Commands
 {
   void command1() {}
   void command2() {}
   void command3() {}
 }
 
 Commands cmds = new Commands();
 char[] cmd = readLine();
 call(cmd, cmd);
 
 Any ideas on how to implement this call() method?
 
 Tnks


This is typically a feature seen in dynamic languages like Python or 
Ruby. In D, the names of methods basically just exist at compile-time. 
You'll have to implement the dispatch mechanism yourself, perhaps 
something like:

void call(Commands c, char[] cmd) {
     switch(cmd) {
         case "command1":
             c.command1();
             break;
         case "command2":
             c.command2();
             break;
         case "command3":
             c.command3();
             break;
         default:
             assert(false, "bad command!");
     }
}

-- 
Kirk McDonald
http://kirkmcdonald.blogspot.com
Pyd: Connecting D and Python
http://pyd.dsource.org

Derek Parnell <derek nomail.afraid.org> writes:

On Tue, 26 Jun 2007 22:28:31 -0400, Lurker #5 wrote:

 One more thing... How can I call a method by name? I was looking at
 the ClassInfo but I cant' find a way to call a method like this:
 
 class Commands
 {
   void command1() {}
   void command2() {}
   void command3() {}
 }
 
 Commands cmds = new Commands();
 char[] cmd = readLine();
 call(cmd, cmd);


The names of the methods and functions are 'lost' during the compilation
process, so you might like to set up your own name to function mapping.

Something like this I find useful...

// --------------------
import std.stdio;

// Here are the definition of the known commands.
void command1()
{
   writefln("Cmd #1");
}

void command2()
{
   writefln("Cmd #2");
}

void command3()
{
   writefln("Cmd #3");
}

void function()[string] RMap; // List of commands, mapped by name.

// Call a command.
void call(string cmdname)
{
    if (cmdname in RMap)
    {
        writef("Calling '%s': ", cmdname);
        RMap[cmdname]();
    }
    else
    {
        throw new Exception("'" ~ cmdname ~ "' is not mapped to a
command.");
    }
}

// Initialize the Name -> Command mapping
static this()
{
    RMap["One"]     = &command1;
    RMap["Two"]     = &command2;
    RMap["Three"]   = &command3;
}

void main()
{

    // Invoke some commands to test it.
    call("Two");
    call("One");
    call("One");
    call("Three");
    call("Four"); // Should fail 'cos not mapped

}
// ---------------

-- 
Derek
(skype: derek.j.parnell)
Melbourne, Australia
27/06/2007 1:40:20 PM

Robert Fraser <fraserofthenight gmail.com> writes:

http://flectioned.kuehne.cn/

Check there for info about D's runtime reflection capabilities. I'm not _sure_
if flectioned supports it or not, but I think so.

Lurker #5 Wrote:

 One more thing... How can I call a method by name? I was looking at the
ClassInfo but I cant' find a way to call a method like this:
 
 class Commands
 {
   void command1() {}
   void command2() {}
   void command3() {}
 }
 
 Commands cmds = new Commands();
 char[] cmd = readLine();
 call(cmd, cmd);
 
 Any ideas on how to implement this call() method?
 
 Tnks