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DeveloperX
202192397
Joined: 04 May 2003
Posts: 1626
Location: Decatur, IL, USA
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 Posted: Wed May 07, 2003 7:48 am Post subject: Scripting Language |
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What is a good start for implementing a scripting language?
I've tried the whole:
$command
%characterchange
concept already (via kakurots tut)
any good advice?
Mind you this will be implemented in either QB or C/C++
Though, remember it is DOS.
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DrunkenCoder
Demon Hunter
Joined: 29 May 2002
Posts: 559
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| Posted: Wed May 07, 2003 12:23 pm Post subject: |
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well with the limited data-handling capabilities and the selfimposed limits you're living under I actually dubt that anything more advanced would be really doable esp. If you think in just having it interpreted instead of compiled to bytecode...
but hey, anything that floats your boat...
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Tenshi
Everyone's Peachy Lil' Bitch
Joined: 31 May 2002
Posts: 386
Location: Newport News
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| Posted: Wed May 07, 2003 4:10 pm Post subject: |
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- What, you mean you're not going to convert your scripts to byte-code? You can do so much with Byte-codes. Without getting too particular about my scripting engine (done in QB), I have scripts like this:
| Code: | MASTER Test Script 2; 0; 0; 0;
script.begin
#load(weather) SNOW
load(map) "Mapper"
script.end |
- This is a "master" script. My system allows only for one "master" script , but I allow for up to 9 subscripts ('cause really, I don't need anything beyond that). Since scripts are run straight from the file ( to avoid bytecode errors from trying to load them into XMS, that was pissing me off ), I only need an array of Strings to point to each file being used, and a couple other environment variables, like which script is being parsed currently, and what line it's on, etc. etc. This script here sets up the environment, and then tells it to load the map "Mapper" (The weather line is commented out with the # sign). The map engine starts, and since the script ends, there's not much anything else to do except run around the map until the user ends the game.
- Here's something a bit more in-depth, an item script:
| Code: | ITEM Turbo Potion;
script.begin
# Use Engine's target.
acquire_target ON
# Check to see if in battle or not
condition(in_battle) 1 3
# If Has Slot "Medic" (43), then double power.
condition(has_slot) USER USER 43 1 2
set_hp TARGET TARGET + 2000
# Else... normal power.
set_hp TARGET TARGET + 1000
acquire_target OFF
script.end |
- My compiler uses a series of tables to turn keywords and numbers into respective byte-codes, and knows whether or not to use one byte, 2, 3, 4, or an arbitrary number, as if for a string ( only allow fixed-length strings, to be easy on myself). It also handles "aliases" and strings differently. ON and "ON" are two different things. A string without quotes means that the compiler should look in the table of "string - value" listings, while with quotes means it should interpret it as-is.
- However, in essense, my scripting engine is very simple, it only handles things as "Command [param, param, param, ...]". I could make it do more, but hey, this is good enough. Commands are set up as Tree + action, for example, Load(map) is under the FILE tree, and is Action #9 or something... so I use two bytes for command.
- Umm, I don't know how useful this was. =T I'm going to be writing an Object-oriented scripting engine, next, but that will be for my MMORPG.
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akOOma
Wandering Minstrel
Joined: 20 Jun 2002
Posts: 113
Location: Germany
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| Posted: Wed May 07, 2003 7:59 pm Post subject: |
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Hey Tenshi,..,this sounds very interesting. Next time I talk to you per AIM, I will ask you some questions 'bout compiling scriptin' code...
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janus
Mage
Joined: 29 Jun 2002
Posts: 464
Location: Issaquah, WA
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| Posted: Wed May 07, 2003 11:51 pm Post subject: |
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You definitely should try for a bytecode-based system... they're way faster and they use less RAM for parsing.
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DrV
Wandering Minstrel
Joined: 15 Apr 2003
Posts: 148
Location: Midwest US
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| Posted: Thu May 08, 2003 12:44 am Post subject: |
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Yeah, even *real* scripting languages (lol) use bytecodes - for example, Perl, and *gasp* VB (before version 5). So they really are a good thing...
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Rainer Deyke
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Joined: 05 Jun 2002
Posts: 672
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| Posted: Thu May 08, 2003 12:51 am Post subject: |
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Actually for a small, non-speed-critical scripting language the Interpreter Pattern (see: Design Patterns) can be just as effective as byte-code with less work. My first scripting language was based on the Interpreter Pattern, it only took me a little over a day to write, and it worked really well.
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DeveloperX
202192397
Joined: 04 May 2003
Posts: 1626
Location: Decatur, IL, USA
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Tenshi
Everyone's Peachy Lil' Bitch
Joined: 31 May 2002
Posts: 386
Location: Newport News
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| Posted: Thu May 08, 2003 10:30 pm Post subject: |
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- You can use mine if you like, you'd need to customize portions of it, but it's kind of flexible. It all depends on what it is you're looking for and what kind of functionality you need.
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DeveloperX
202192397
Joined: 04 May 2003
Posts: 1626
Location: Decatur, IL, USA
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| Posted: Thu May 08, 2003 10:33 pm Post subject: |
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| Tenshi wrote: | | - You can use mine if you like, you'd need to customize portions of it, but it's kind of flexible. It all depends on what it is you're looking for and what kind of functionality you need. |
there a url? or you want to email it to me?
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BigManJones
Scholar
Joined: 22 Mar 2003
Posts: 196
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| Posted: Fri May 09, 2003 12:59 am Post subject: |
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There is a really good article in one of the first issues of pixelate about implementing a scripting language. And for C/C++ you can use something like lua (its pretty tough to get going on awindows/gcc compiler though). Scripting was what kept my mini-compo entry from getting submitted :(
Bytecode would be super simple - you can load the entire script and have an array of 'variables' and a p.c. (ie program counter) that would tell you which line is next - by alter the pc you can implement all the control structures (for-next, do-while, while, if then and case) like you would in 68hc11 assembler. You could even have a jump-to-subroutine and return-from-subroutine stack. This should be doable in qbasic (I don't know qbasic though)
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janus
Mage
Joined: 29 Jun 2002
Posts: 464
Location: Issaquah, WA
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| Posted: Fri May 09, 2003 6:11 am Post subject: |
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| DeveloperX wrote: | | Would someone want to contribute a scripting system to the PROJECT? |
If it wasn't unplanned and using a decades-old toy language, sure. ;) I'd be glad to help you out, but I'm sure as hell not writing your code for you, especially not in a crippled language I haven't used in nearly 6 years.
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akOOma
Wandering Minstrel
Joined: 20 Jun 2002
Posts: 113
Location: Germany
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| Posted: Sat May 10, 2003 11:31 am Post subject: |
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I just want to try something with compiling scripts to bytecode. It would be cool to code something like that..
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Tenshi
Everyone's Peachy Lil' Bitch
Joined: 31 May 2002
Posts: 386
Location: Newport News
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| Posted: Sat May 10, 2003 3:36 pm Post subject: |
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- It's "cool" I guess. The type of scripting I used made for an easy compiler (though I added a billion things to it to make it kinda complex), but if you want to get nasty with complex statements (like X = Y + 1) then I'm not at that point yet. My 32-bit compiler will be.
DeveloperX, I emailed ya.
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DeveloperX
202192397
Joined: 04 May 2003
Posts: 1626
Location: Decatur, IL, USA
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| Posted: Sun May 11, 2003 5:59 am Post subject: |
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| Tenshi wrote: |
DeveloperX, I emailed ya. |
Uhm, I have no emails from you.
Are you sure that you sent it to the correct address?
ccps@SoftHome.net
is my email address.
I guess you sent it to my hotmail account?
I don't use it for email, only MSN Messenger.
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