Thanks for the suggestion, but, as you may have guessed, this has been
considered. ;) Yet, creating an entire scripting engine isn't the goal of
EventScripts. There are lots of different scripting engines out there, and they
definitely have their place for administrators who understand coding.
EventScripts is trying to be the middle-ground between a structured/scoped
language and the console commands they know and love. As I mentioned below, ES
doesn't yet support looping and the like and may never do so--- it's not
intended to be a full-powered scripting language.
With EventScripts, we're trying to enhance the console commands so that even
everyday normal console/rcon commands and normal autoexec.cfg/server.cfg files
can take advantage of very simple logic and variable expansion. We don't need
everything a scripting language can do, we just want some basic enhancements to
the command console. Most of these console enhancements would be along the lines
Valve was already been moving, e.g. with "setinfo" and "incrementvar".
Yet, even in the case of a full blown scripting language, not having
InsertCommand() means that any scripts/commands that you wished to invoke via a
normal Valve cfg file would have the same ordering problem if they needed to
pass commands back to the server (e.g. exec, changelevel, kickid, etc). These
commands would execute *after* the current .cfg file was totally resolved and
not in-place. This wouldn't be intuitive and would likely cause problems! It
wouldn't be a problem if you didn't allow the console to launch scripts, but the
server console is a great place for invoking things like that (especially
remotely).
*** TO CLARIFY, this isn't a problem just for scripting engines! *** It's a
problem for ANY PLUGIN that uses console commands and needs to interact with the
console. Let's say I wrote a console command "mattie_exec" that took Con_Argv(1)
and passed it to exec with a different directory prefix (e.g. my mod's
directory).
// server.cfg
mattie_exec blah.cfg
exec load_plugins.cfg
// end of server.cfg
Now, the mattie_exec command, all it does is call engine->ServerCommand("exec
matties_mod\blah.cfg\n"). In this case, the console would execute like this:
1. (contents of server.cfg added to the queue around LevelInit())
2. mattie_exec runs (places "exec mattie_mod\blah.cfg" at end of queue)
3. exec load_plugins.cfg runs (all plugins activated, configured, etc)
4. exec mattie_mod\blah.cfg runs
You see that even though the mattie_exec command was placed in a certain order
in the cfg file, it's irrelevant. Any server commands those commands rely upon
cannot be activated until after the entire .cfg file has been processed. This
means that if the "load_plugins.cfg" relied upon any settings created in
blah.cfg, there's no way at all to get it to work short of bypassing the plugin
commands.
Admittedly, this is a simple example, but it underscores the issue outside of a
scripting context. Plugin console commands could be calling back to any number
of other console commands. We all have access to ServerCommand(), right? Well,
just like Valve, we need it's sister command in order to create proper console
commands. Sometimes we don't care about ordering, so ServerCommand() might be
appropriate, but many times ordering *will* be important. We truly need
ServerInsertCommand(), and I hope everyone can see that.
Thanks for your help and for reading this far,
-Mattie
----- Original Message -----
From: "Jeremy Swigart" <[EMAIL PROTECTED]>
To: <hlcoders@list.valvesoftware.com>
Sent: Friday, June 10, 2005 7:17 AM
Subject: Re: [hlcoders] Examples of uses for IEngine->ServerInsertCommand()
Have you considered using a scripting language such as lua or
gamemonkeyscript or another one that supports fake threading?
Specifically you might be interested in their ability to execute over
many frames, yet still be written in a top down manner. Here's an
example of GMS, which I use in my bot.
/ server.cfg
if(sv_gravity > 800)
{
exec("reset_grav.cfg");
echo("gravity reset");
yield(); // suspend execution of the script till the next frame, can
also do sleep() commands
}
else
{
echo("gravity is fine");
}
echo("this happens the frame after the gravity is reset, or right away
if the exec didnt happen");
Everything you do and much more would be possible using the features
of an existing scripting language, and with it you'd get the power of
conditionals, tables, loops, and much more.
Just an idea.
J
On 6/9/05, Mattie Casper <[EMAIL PROTECTED]> wrote:
As promised, this email contains examples of the sorts of things that plugin
authors cannot manage in Source without some method to insert commands at the
beginning of the server command queue. This ability is vital for any plugin
wishing to create meta console commands. I.e. commands like alias, exec,
incrementvar, etc.
Variable expansion --
------------------------
EventScripts makes extensive use of variable expansion for its console
commands, and it's crippled without InsertCommand(). There's no way to
arrange
for expanded commands to execute right away before the rest of a config file.
For example, let's say I added the following lines to a .cfg file (e.g.
server.cfg):
// server.cfg
// let's say 'mypluginvar' is a variable exposed by my plugin
mypluginvar "ClanMatch"
expandvars echo *** mypluginvar equals %mypluginvar%
echo *** The above line should say "mypluginvar equals ClanMatch"
echo *** server.cfg is completely done. should see nothing else.
// end server.cfg
So, if my plugin's 'expandvars' command expanded variables in the string
provided to it and then passed it back to the server, the only mechanism it
can
use is ServerCommand(). This will place it AFTER everything else in the
queue.
As such, the output would be:
*** The above line should say "mypluginvar equals ClanMatch"
*** server.cfg is completely done. should see nothing else.
*** mypluginvar equals ClanMatch
This is definitely not what someone writing a .cfg file would be expecting.
They
expect the commands to go in order of writing. EventScripts supports a great
deal of variable expansion, but there's no support for intuitive ordering.
This
example is trivial compared to the complicated scripts people are creating.
It
really weakens the plugin when admins can't trust that your variables will be
expanded properly in relation to other commands in the cfg file.
-------------------------
Conditional expressions --
-------------------------
EventScripts supports conditional expressions. These are also hindered
without
InsertCommand(). The order of execution again gets all out of phase. For
example, let's say I added the following lines to a .cfg file (e.g.
server.cfg):
// server.cfg
// let's say my plugin exposes an "exec_if" command
exec_if sv_gravity > 800 then reset_grav.cfg
echo *** sv_gravity was set back to 800 by increase_grav.cfg
exec_if sv_gravity > 800 then something_wrong.cfg
// end of server.cfg
In this case, the plugin command "exec_if" would test the condition
"sv_gravity
> 800" and then use, sadly, ServerCommand() to place "exec reset_grav.cfg"
in
the queue where it could reset the gravity back to 800. Unfortunately, this
goes
to the very end of the queue, so the rest of the server.cfg executes first.
This
means the second conditional will STILL see sv_gravity incorrectly because it
goes through the server command queue like this:
1. exec_if
2. echo
3. exec_if
4. exec reset_grav.cfg
5. exec something_wrong.cfg
#5 should never happen-- and #4 should happen before the 'echo' does. Yet we
can't do this because InsertCommand() isn't yet available to plugin writers.
-------------------------
Loops --
------------------------------
EventScripts does not yet support loops, but these would also be possible
if
Valve provided a way to insert commands at the beginning of the queue.
Without
it, you cannot be certain that the loop lines will execute before the next
line
in a script.
------------------------------
Enhanced versions of alias, exec, etc
-----------------------------
EventScripts doesn't do this yet, but if I wanted to create an enhanced
version
of these Valve commands, the new commands will always be deficient without
InsertCommand(). For example, if we wanted to write an optimized "exec"
command
that cached the .cfg file in memory on the first execution and then always
ran
it from memory whenever called (to avoid refetches from disk):
// server.cfg
memexec only_changes_on_reboot.cfg
exec load_plugins.cfg
// end of server.cfg
In this case, simulating "exec" is impossible if I wish to maintain the order
of
a .cfg file. I.e., we can't cycle through the lines of the file and have them
inserted at the beginning of the command queue like Valve does. This means
that
anytime we try to add the lines, they'll always fall *after* every other line
in
the .cfg file. Order is important at times for plugins and the like, and
without
that we just can't improve upon the console commands very well.
-----------------------------
Anyway, I'm going to stop now because this is getting so long that I'm sure
no
one will read it. ;) Rest assured that all of these things and more would be
possible if Valve enhanced the Source SDK to include a mechanism for adding
commands to the beginning of the queue.
Anyone curious about using EventScripts, you can find my forums here:
http://www.sourcemod.net/forums/viewforum.php?f=20
Thanks for reading this far. Maybe it will give other coders some ideas, too,
-Mattie
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