Extracting info from a slash command

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Contents 1 The Concept 2 The Code 3 How it Works 4 Conclusion 5 An Example 6 Parsing Into Tables 7 Also See

The Concept

Lets say you have this nice addon you're creating, but you come to the point where just one argument on the slash command just isn't doing it. IE you need to use /myaddon my command goes here, rather then just /myaddon command. There are many ways you can solve this issue, but here's one very simple one I have found.

The Code

This requires two specific Functions. A 'Cmd/SubCmd' function, and an 'Argument' function (last one optional).

 function MyAddon_GetCmd(msg)
 	if msg then
 		local a,b,c=strfind(msg, "(%S+)"); --contiguous string of non-space characters
 		if a then
 			return c, strsub(msg, b+2);
 		else	
 			return "";
 		end
 	end
 end
 function MyAddon_GetArgument(msg)
 	if msg then
 		local a,b=strfind(msg, "=");
 		if a then
 			return strsub(msg,1,a-1), strsub(msg, b+1);
 		else	
 			return "";
 		end
 	end
 end

How it Works

The way this works, is it first checks to see if a command was entered. If so, then it extracts just the first cmd/subcmd for return. This is very useful in recursively deep functions, IE:

 /myaddon add user name=tigerheart

would be processed as:

 msg = "add user name=tigerheart";
 local Cmd, SubCmd = MyAddon_GetCmd(msg);

would return:

 "add" as Cmd
 "user name=tigerheart" as SubCmd

so we send on the subcmd to the next processor for the "add" routines, which again will parse this as Cmd and SubCmd. This one parses:

 "user" as Cmd
 "name=tigerheart" as SubCmd.

we now get to the final stage. This function will process the subcmd with 'GetArgument'. To call GetArgument you would do:

 Argument, Answer = MyAddon_GetArgument(subcmd);

Which would return:

 "name" as Argument
 "tigerheart" as Answer

Conclusion

I hope this helps, its come in very handy for my purposes. If you use this I would love if you could at least credit me in a comment somewhere.

My mod BattleInfo uses this actively, in a slightly modified form.

An Example

Here's a simple example of how this is used, in context

 function MyAddon_SlashHandler(msg)
 	local Cmd, SubCmd = MyAddon_GetCmd(msg); --call to above function
 	if (Cmd == "help") then
 		MyAddon_DisplayHelp();
 	elseif (Cmd == "add") then
 		MyAddon_AddUser(SubCmd);
 	else
 		MyAddon_DisplayHelp();
 	end;
 end;
 function MyAddon_AddUser(msg)
 	local Cmd, SubCmd = MyAddon_GetCmd(msg); --call to above function
 	if (Cmd == "user")  then
 		local Argument, Answer = MyAddon_GetArgument(SubCmd); --call to above function
 		if (Argument == "name") then
 			MyAddon_AnotherRoutine(Answer);
 		end;
 	end;
 end;

And so on, until you get what you need. This way you can split up each 'subcommand' into a separate function, quickly and easily. This also helps to modulize the code so it's easier to read, easer to debug, and later, to maintain.

Also, as for case-correction, Cmd will be converted to lower case, whereas subcmd is left untouched.

Enjoy,

Parsing Into Tables

If you want to put each word into a table, use gsub or string.gmatch.

With gmatch, use it as an iterator in a loop.

 function MsgToTable( msg )
 	if not msg then return end
 	local t = {};
 	for w in string.gmatch( msg, "%S+" ) do
 		tinsert( t, w )
 	end
 	return t;
   end

With gsub, pass an anonymous function as its 3rd argument.

 function MsgToTable( msg )
 	if not msg then return end
 	local t = {};
 	gsub( msg, "%S+", function(w)
 		tinsert( t, w )
 	end)
 	return t;
 end

Both functions return a table. Thus you can use it in an assignment statement. MyAddon_MsgTable = MsgToTable(msg);

Also See

• GetWords user-defined function.
• strfindt user-defined function.