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- Subject: Re: using LuaCOM and enumarators
- From: Vinicius da Silva Almendra <almendra@...>
- Date: Wed, 6 Aug 2003 13:48:59 -0300 (BRT)
Hello,
The collection you are trying to use can't be "indexed" (with Item(n)).
I tried that in VB and did not work too... The solution is to use the
enumerator (VB uses it in its for...each...next), but LuaCOM does not
implement this yet. I'm working on this now in perhaps in the end of the
week I'll have a working solution.
Best regards,
Vinicius Almendra
TeCGraf/PUC-Rio researcher
Original Message
----------------
I'm trying to get LuaCOM to work, and having some problems... has anyone had
any success enumerating collections? For example, I'm trying to get a list
of drives:
fso = luacom.CreateObject("Scripting.FileSystemObject")
drives = fso.Drives
This returns a collection object, as expected. I can index them by name:
cdrive = drives:Item("C")
But numeric index does not seem to work (and as far as I can see, should do)
firstdrive = drives:Item(1)
LuaCOM Exception in file tLuaCOM.cpp at line 661: COM exception: The
parameter is incorrect.
COM exception: The parameter is incorrect. (file tLuaCOM.cpp, line 661)
I also cannot seem to get a working enumerator object. How do I do this?
drives:GetEnumerator() doesn't exist, and drives:_GetEnum returns a userdata
object, with nothing I can call. The metatable for this object seems to
onbly contain "eq" and "gc", and the gc seems to crash...
Is there any way I can actually enumerate a collection, as it is really hard
to do a lot of things without this facility.
Thanks!
Love, Light and Peace,
- Peter Loveday
Director of Development, eyeon Software
------------------------------
Message: 9
Date: Tue, 5 Aug 2003 15:15:47 -0400
From: Thatcher Ulrich <tu@tulrich.com>
Subject: Re: SDL package (namespace problem)
To: Lua list <lua@bazar2.conectiva.com.br>
Message-ID: <20030805191547.GD696@tulrich.com>
Content-Type: text/plain; charset=us-ascii
On Aug 05, 2003 at 01:17 -0400, Peter Loveday wrote:
> My view is that modules should not be allowed to place things in the global
> namespace. Obviously we can't enfore it, but it can be strongly
> discouraged.
I agree with this.
> I think SDL.LoadBMP() is far more consistant with anything else in
> LuaCheia. It is a lot more obvoius to a user that a given module
> has functions within a given table, and has the added bonus that
> dumping the contents of that table gives you a quick list of
> functions available in the module.
Seconded. I personally don't mind SDL.SDL_LoadBMP(), especially if it
takes some load off the module maintainer, but I agree SDL.LoadBMP()
looks nicer.
--
Thatcher Ulrich
http://tulrich.com
------------------------------
Message: 10
Date: Tue, 5 Aug 2003 15:24:38 -0400 (EDT)
From: Diego Nehab <diego@tecgraf.puc-rio.br>
Subject: Re: select implementation for a "file descriptor set"
To: lua@bazar2.conectiva.com.br
Message-ID: <Pine.LNX.4.55.0308051523550.30927@opus.cs.princeton.edu>
Content-Type: TEXT/PLAIN; charset=US-ASCII
Hi,
> This is tricky on Windows... certainly you can wait for multiple
> objects such as file I/O, serial, sockets etc; but not with a
> select(), which is only valid for sockets. This is one area of
> Windows that's a real PITA; the lack of a single signal/messaging
> system for timers, UI events, sockets, asyc I/O, semaphores etc...
> they all have different mechanisms.
Yes, this is why I didn't include a generic select in LuaSocket. I could
even add support for select on Lua file objects but that would only work
on Linux. I might do that in the future.
BTW, in case you are wondering how the Cygwin people implemented select
on Windows... At each call, they actually sort all "file desctiptors"
according to category (socket, file, handle to other stuff etc), spawn
one thread to wait on each category and then combine the results. This
is *not* an option for LuaSocket.
[]s,
Diego.
------------------------------
Message: 11
Date: Tue, 5 Aug 2003 15:25:34 -0400 (EDT)
From: Diego Nehab <diego@tecgraf.puc-rio.br>
Subject: Re: ANN: luacheia alpha1 release
To: lua@bazar2.conectiva.com.br
Message-ID: <Pine.LNX.4.55.0308051524470.30927@opus.cs.princeton.edu>
Content-Type: TEXT/PLAIN; charset=US-ASCII
Hi,
> We currently make one change to the stock Lua5, which is to extend
> "loadlib()" so that it supports dylib's under OSX. So far none of the
> included modules rely on loadlib() so that's not really an obstacle.
Just out of curiosity, what did you have to change to get loadlib to
work? I am using the dlcompat here and I think it works fine. Except, of
course, for the damn "_" in the beginning of exported function names,
but that can be taken care of in a startup module written in Lua.
[]s,
Diego.
------------------------------
Message: 12
Date: Tue, 5 Aug 2003 16:31:54 -0300
From: Luiz Henrique de Figueiredo <lhf@tecgraf.puc-rio.br>
Subject: Re: SDL package (namespace problem)
To: lua@bazar2.conectiva.com.br
Message-ID: <200308051931.QAA10840@lua.tecgraf.puc-rio.br>
Another advantage of stripping library prefixes in Lua bindings is that it
automatically allows OO syntax, if the library functions always receive a
handle as the first argument. I've exploited this in my libraries for gdbm,
md5, and pdf.
So, for instance, it's much cleaner to write
d:digest()
than
d:md5_digest()
or even
md5_digest(d)
On the other hand, if the Lua binding uses luaL_reg structs to define the
binding names, then it's pretty simple to traverse it and register the
functions as globals with the correct prefix attached. In this way, you
get both options.
--lhf
------------------------------
Message: 13
Date: Tue, 5 Aug 2003 15:36:56 -0400
From: "Peter Loveday" <peter@eyeonline.com>
Subject: Re: SDL package (namespace problem)
To: "Lua list" <lua@bazar2.conectiva.com.br>
Message-ID: <007101c35b88$ee39a160$2802a8c0@loveboy>
Content-Type: text/plain; charset="iso-8859-1"
> On the other hand, if the Lua binding uses luaL_reg structs to define the
> binding names, then it's pretty simple to traverse it and register the
> functions as globals with the correct prefix attached. In this way, you
> get both options.
Perhaps some standard means for a library to 'globalise' itself would be
useful for people who like such things?
Kind of along the lines of the compat stuff for Lua4 code, but per-module.
So by default when loading a module, you get it in a namespace, but by using
the module 'globalise' call, you can expose it. Something like:
cheia.load("SDL")
SDL:Gobalise()
By default this wopuld simply place any given module into global functions
with it's module prefix (SDL.LoadBMP gets put into SDL_LoadBMP() etc).
However a Module could override this to allow for other behaviour, or adding
some other 'compatibility' stuff (as the compat.lua layer does)
note, I don't think it should actually be called 'globalise' :)
Love, Light and Peace,
- Peter Loveday
Director of Development, eyeon Software
------------------------------
Message: 14
Date: Tue, 5 Aug 2003 16:41:50 -0300
From: Luiz Henrique de Figueiredo <lhf@tecgraf.puc-rio.br>
Subject: Re: SDL package (namespace problem)
To: lua@bazar2.conectiva.com.br
Message-ID: <200308051941.QAA10880@lua.tecgraf.puc-rio.br>
>Perhaps some standard means for a library to 'globalise' itself would be
>useful for people who like such things?
function globalise(a)
local t=_G[a]
for k,v in t do
_G[a.."_"..k]=v
end
end
globalise"SDL"
--lhf
------------------------------
Message: 15
Date: 05 Aug 2003 22:02:00 +0100
From: mjscod@gmx.de (Mark Junker)
Subject: tolua5: problem w. GC and user data
To: lua@bazar2.conectiva.com.br
Message-ID: <8rGH5TYe+GB@gmx.de>
Content-Type: text/plain; charset=US-ASCII
Hi,
I tested toLua 5 and found a problem. We wanted to use Lua 5 in an embedded
environment with limited memory. We make extensive use of classes exported to
Lua as user data. It was no problem to create a pkg file and calling the C++
class members wasn't a problem at all.
However, the problem I've found was that in the following source, the
TTestData objects will only be released (deleted from heap memory) when the
lua_close(L) function is called.
So we ran out of memory when we don't open and close the lua interpreter at
the beginning and the end of the script execution which is a big perfomance
problem.
How can I avoid the need to open/close lua?
---------------------------- C++ header ------------------------------
class TTestData {
public:
unsigned getValue(void) const;
};
class TTest {
public:
unsigned getCount(void) const;
TTestData getData(unsigned index) const;
};
---------------------------- C++ header ------------------------------
---------------------------- C++ source ------------------------------
unsigned TTestData::getValue(void) const
{
return 1234;
}
unsigned TTest::getCount(void) const
{
return 1234;
}
TTestData TTest::getData(void) const
{
return TTestData();
}
---------------------------- C++ source ------------------------------
---------------------------- toLua pkg ------------------------------
class TTestData {
unsigned getValue(void) const;
};
class TTest {
unsigned getCount(void) const;
TTestData getData(unsigned index) const;
};
---------------------------- toLua pkg ------------------------------
---------------------------- lua script ------------------------------
local count = var:getCount() - 1
for i=0,count do
local data = var:getData(i);
print(data.getValue())
end
---------------------------- lua script ------------------------------
Best regards,
Mark Junker
------------------------------
Message: 16
Date: Tue, 05 Aug 2003 22:08:16 +0200
From: Martin Spernau <martin@traumwind.de>
Subject: Re: ANN: luacheia alpha1 release
To: Lua list <lua@bazar2.conectiva.com.br>
Message-ID: <3F300EB0.3070403@traumwind.de>
Content-Type: text/plain; charset=us-ascii; format=flowed
>>Also since IUP also contains the Lua source, and you want to make
>>IUP a module, at least one of you will have to concede...
>>
>>
>
>Agreed. I imagine a modulized IUP would use the luacheia build
>system, and clearly it would need to link to the same Lua libs as the
>core. AFAIK no luacheia developers have looked at this yet. I did
>some wxLua work though so the issues are probably similar.
>
>
The reason I haven't looked into IUPLua yet is a lack (?) of examples,
but maybe I haven't looked hard enough...
With wxLua the benefits are instanty visible, it comes with a nice
Lua-Editor as default and many nice GUI examples. Maybe some obvious
usage-examples of IUP/Lua would be helpfull...
-Martin
>Note: we would love it if somebody volunteered to adapt IUP as a
>module for luacheia!
>
>(Ditto for debugging the wxLua module, adding other modules, etc!)
>
>
>
>> * rewriting wrapper names (for example, SDL.LoadBMP instead of
>>SDL.SDL_LoadBMP)
>>
>>
>
>Yup, noted. Basically this is up to whoever the module maintainer is.
>If it's me, I generally try to change as little as possible, and set
>myself up for as little maintenance work as possible, if I'm working
>with an existing lib.
>
>In the case of SDL, Asko Kauppi is in charge of the module now. When
>I made a Lua4 wrapper, I used the double namespace because tolua
>didn't have an easy way to remove the prefix. Plus symbols like
>SDLK_* would have needed extra attention.
>
>
>
------------------------------
Message: 17
Date: Tue, 05 Aug 2003 16:49:52 -0700
From: Ando Sonenblick <ando@spritec.com>
Subject: "Locking" global variables?
To: Lua list <lua@bazar2.conectiva.com.br>
Message-ID: <BB5590B0.E97E%ando@spritec.com>
Content-Type: text/plain; charset="US-ASCII"
Gang,
Is there a way in Lua to lock a global variable after initializing it so
that trying to reassign it will fail?
We'd like to prevent inadvertent reassignment of key global variables by
some unaware scriptor...
Thx,
Ando
-----------------
SpriTec Software
www.spritec.com
------------------------------
Message: 18
Date: Tue, 5 Aug 2003 17:05:58 -0700
From: "Nick Trout" <nick@rockstarvancouver.com>
Subject: RE: What is differential inheritance? An example in Lua,
Please.
To: "Lua list" <lua@bazar2.conectiva.com.br>
Message-ID:
<911F8C8EB7A8084AAEDD55CEDC54D8F80CB53E@iggy.rockstarvancouver.com>
Content-Type: text/plain; charset="us-ascii"
> From: Vijay Aswadhati [mailto:wyseman@pacbell.net]
> Sent: Saturday, August 02, 2003 9:35 AM
> To: 'Lua list'
> Subject: What is differential inheritance? An example in Lua, Please.
>
> Steve Dekorte in a posting regarding windowing toolkits
> (Lui) mentioned about using Differential Inheritance if
> he were to rewrite Lui again.
> <http://lua-users.org/lists/lua-l/2003-02/msg00365.html>
>
> What is it and can anyone provide a good example in Lua
> OR point me to any appropriate links.
I *think* the reason for the comment is that the Yindo's window library
uses inheritance by delegation, which I can see being slower than moving
to a differential system. Inheritance by delegation works by using a
metamethod to search the parent class for a missing field in the local
class instance - in effect looking to see if you inherited a field. I
think if you moved to a differential system (i.e. make small
differential changes to each specialised class) you would aggregate all
of your fields at instance time to avoid doing the search every time you
need to look for an inherited field.
--nick
------------------------------
Message: 19
Date: Tue, 5 Aug 2003 17:54:30 -0700
From: "Nick Trout" <nick@rockstarvancouver.com>
Subject: RE: wxLua on OS X?
To: "Lua list" <lua@bazar2.conectiva.com.br>
Message-ID:
<911F8C8EB7A8084AAEDD55CEDC54D8F80CB53F@iggy.rockstarvancouver.com>
Content-Type: text/plain; charset="us-ascii"
> What I am looking for is a toolkit that is totally devoted to GUI and
> nothing else. For example no sockets, no threading and synchronization
> facilities.
But when you are porting, or maintaining, a cross platform application
there are other issues, like threading. So I can see how these become
part of such a code base, although they should probably be a separate
library.
> I have looked at TkLua, wxLua, Lua FLTK, Lui and IUP; none of the
current
> solutions satisfy the requirements I have (in my mind).
>
> On the wild side, I have been spending some time investigating at
> potential
> candidates that meet the requirements at least from what I have read
about
> them. These are in no particular order:
> -- The fox toolkit <http://www.fox-toolkit.org>
> -- Java SWT from eclipse project
> <http://www.eclipse.org/articles/index.html>
I had a look for one a while ago as I was trying to write a cross
platform IDE for Lua. Perhaps this would be of interest to you:
http://lua-users.org/wiki/VisLuaImplementation
When I looked at Fox it wasn't working on as many platforms, or has such
a large useful widget set as WX. Wouldn't SWT require a Java VM install?
Do you mean AWT or SWT - as it's from Eclipse? AWT uses native
non-portable widgets.
> However there is no gaurantee that they will remain so. For example
the
> author of fox toolkit is currently investigating on how to provide a
> HTML browser widget and I am sure any implementation would lead to
adding
> socket support to the library thus making even this toolkit a bit
"fat".
> An ideal marriage would be to find a toolkit that provides absolutely
> bare minimum of GUI abstractions and platform portability and the rest
> gets built using Lua itself. That is why I am leaning towards porting
> SWT to Lua, since only the very low level widget code is written
> in "C" and the rest is written using Java. The trouble is that I am
> still learning Lua and this is not a trivial excercise. And I do not
> want to use "toLua" since that again introduces a dependency.
I've settled on WX and I'll accept its size and shortcoming because it
has such good support, is bound to lots of scripting languages and is so
portable.
--nick
------------------------------
Message: 20
Date: Tue, 05 Aug 2003 21:44:53 -0400
From: Peter Shook <pshook@sympatico.ca>
Subject: Re: "Locking" global variables?
To: Lua list <lua@bazar2.conectiva.com.br>
Message-ID: <3F305D95.1020108@sympatico.ca>
Content-Type: text/plain; charset=us-ascii; format=flowed
=== FAQ ===
Ando Sonenblick wrote:
> Gang,
>
> Is there a way in Lua to lock a global variable after initializing it so
> that trying to reassign it will fail?
>
> We'd like to prevent inadvertent reassignment of key global variables by
> some unaware scriptor...
If you want to make all globals readonly, see lua-5.0/test/readonly.lua
If you want to make only a few variables readonly, try something like this:
$ cat z.lua
local ReadOnly = {
x = 5,
y = 'bob',
z = false,
}
local function check(tab, name, value)
if ReadOnly[name] ~= nil then
error(tostring(name) ..' is a read only variable', 2)
end
rawset(tab, name, value) -- tab[name] = value
end
-- make some global variables readonly
setmetatable(_G, {__index=ReadOnly, __newindex=check})
$ lua -lz -i
>
> = x,y,z
5 bob false
> x = 44
stdin:1: x is a read only variable
stack traceback:
[C]: in function `error'
z.lua:10: in function <z.lua:8>
stdin:1: in main chunk
[C]: ?
> z = 99
stdin:1: z is a read only variable
stack traceback:
[C]: in function `error'
z.lua:10: in function <z.lua:8>
stdin:1: in main chunk
[C]: ?
> a,b = 1,2
> = a,b
1 2
>
Here are some similar threads:
http://lua-users.org/lists/lua-l/2003-06/msg00362.html
http://lua-users.org/lists/lua-l/2003-07/msg00298.html
- Peter
------------------------------
Message: 21
Date: Tue, 5 Aug 2003 22:50:26 -0400
From: Thatcher Ulrich <tu@tulrich.com>
Subject: Re: ANN: luacheia alpha1 release
To: Lua list <lua@bazar2.conectiva.com.br>
Message-ID: <20030806025025.GE696@tulrich.com>
Content-Type: text/plain; charset=us-ascii
On Aug 05, 2003 at 03:25 -0400, Diego Nehab wrote:
> Hi,
>
> > We currently make one change to the stock Lua5, which is to extend
> > "loadlib()" so that it supports dylib's under OSX. So far none of the
> > included modules rely on loadlib() so that's not really an obstacle.
>
> Just out of curiosity, what did you have to change to get loadlib to
> work? I am using the dlcompat here and I think it works fine. Except, of
> course, for the damn "_" in the beginning of exported function names,
> but that can be taken care of in a startup module written in Lua.
I'm not the OSX expert, but I think the reason was so that users
wouldn't have to install dlcompat.
Actually I was remembering wrong; I don't think we change the default
loadlib at all. However we have a loadlib-derived wrapper for the use
of loadmodule and gluax which are embedded in the luacheia
interpreter. Here's the wrapper code we use:
http://cvs.sourceforge.net/cgi-bin/viewcvs.cgi/luacheia/luacheia/src/luacheia/loadlib.c?rev=HEAD&content-type=text/vnd.viewcvs-markup
--
Thatcher Ulrich
http://tulrich.com
------------------------------
Message: 22
Date: Tue, 5 Aug 2003 20:44:20 -0700
From: "Vijay Aswadhati" <wyseman@pacbell.net>
Subject: RE: wxLua on OS X?
To: "'Lua list'" <lua@bazar2.conectiva.com.br>
Message-ID: <00ef01c35bcd$05664e80$6601a8c0@integra04>
Content-Type: text/plain; charset="us-ascii"
<snip/>
> When I looked at Fox it wasn't working on as many platforms,
> or has such a large useful widget set as WX.
True. I am not sure if we both looked at it during the same
time period. Lately, however it does have a very nice set of
widgets; the number of users are slowly growing and finally
the author is doing a great job by way of support offered
via the newsgroup.
> Wouldn't SWT require a Java VM install?
Not the way I plan on porting it to Lua. Read on...
> Do you mean AWT or SWT - as it's from Eclipse?
I meant SWT and yes it is from IBM's Eclipse project.
> AWT uses native non-portable widgets.
Hmmm. But I am not planning on porting AWT.
The understanding I have is from looking at the source
code and by reading articles that talk about the design
and motivation of SWT <http://www.eclipse.org/articles/index.html>
SWT differs significantly from the approach taken by Sun. The
approach taken by the Eclipse team is to split the toolkit
into three layers:
- Documented platform independent GUI object model (a.k.a SWT)
that is written in Java. [L1]
- An internal platform specific adaptation layer that is also
written in Java. [L2]*N Where N is the number of platforms.
- A native platform specific bridge layer that is written in "C"
and bridges the internal platform specific Java adaptation layer
to the OS supported GUI system calls. [L3]*N Where N is the
number of platforms.
What I am contemplating on is the following:
- The native platform specific bridge layer written in "C" looks
"very" clean. This layer [L3] needs to be converted to Lua "C".
Labor intensive yes, but nothing that cannot be mapped to Lua
"C" API (as a first approximation). This has to be done for
all N
- Port the entire Java code [L1] to Lua. This is to be done only
once.
- Port the [L2] for all N.
That was the scoop and that also explains my earlier post requesting
a sample for "differential inheritance".
Since Lua is faster than Java (metrics obtained from the "Great Language
Shootout"), I am thinking this should work. But then I could be overlooking
something. However I do believe that having a widget toolkit that was built
for Lua from the ground up would bring in a new wave of fans to Lua just
as Tcl/Tk (which by the way is my definition of an ideal marriage)
did during its sunshine days.
Comments and feedback are welcome.
-- Vijay Aswadhati
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------------------------------
Message: 23
Date: Wed, 06 Aug 2003 20:20:50 +0530
From: "UriBoy b" <deadpoet_me3@lycos.com>
Subject: how does lua apply the new configuration to the original
program?
To: lua@bazar2.conectiva.com.br
Cc: lua@bazar2.conectiva.com.br
Message-ID: <LONDGOMBJIBPKGAA@mailcity.com>
Content-Type: text/plain; charset=us-ascii
hi all...
may i just ask 'how does lua communicate with the original program? i mean, if lua is a configuration languange, and you create a configuration file, how does lua apply the new configuration to the original program it is extending?'
thanks...
=)
____________________________________________________________
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------------------------------
Message: 24
Date: Wed, 06 Aug 2003 20:20:50 +0530
From: "UriBoy b" <deadpoet_me3@lycos.com>
Subject: how does lua apply the new configuration to the original
program?
To: lua@bazar2.conectiva.com.br
Cc: lua@bazar2.conectiva.com.br
Message-ID: <LONDGOMBJIBPKGAA@mailcity.com>
Content-Type: text/plain; charset=us-ascii
hi all...
may i just ask 'how does lua communicate with the original program? i mean, if lua is a configuration languange, and you create a configuration file, how does lua apply the new configuration to the original program it is extending?'
thanks...
=)
____________________________________________________________
Get advanced SPAM filtering on Webmail or POP Mail ... Get Lycos Mail!
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------------------------------
Message: 25
Date: Wed, 06 Aug 2003 20:20:50 +0530
From: "UriBoy b" <deadpoet_me3@lycos.com>
Subject: how does lua apply the new configuration to the original
program?
To: lua@bazar2.conectiva.com.br
Cc: lua@bazar2.conectiva.com.br
Message-ID: <LONDGOMBJIBPKGAA@mailcity.com>
Content-Type: text/plain; charset=us-ascii
hi all...
may i just ask 'how does lua communicate with the original program? i mean, if lua is a configuration languange, and you create a configuration file, how does lua apply the new configuration to the original program it is extending?'
thanks...
=)
____________________________________________________________
Get advanced SPAM filtering on Webmail or POP Mail ... Get Lycos Mail!
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------------------------------
Message: 26
Date: Wed, 06 Aug 2003 11:56:46 -0300
From: Alex Sandro Queiroz e Silva <ventonegro@ventonegro.org>
Subject: Re: how does lua apply the new configuration to the original
program?
To: Lua list <lua@bazar2.conectiva.com.br>
Message-ID: <3F31172E.5000108@ventonegro.org>
Content-Type: text/plain; charset=ISO-8859-1; format=flowed
Hallo,
UriBoy b wrote:
>hi all...
>
> may i just ask 'how does lua communicate with the original program? i mean, if lua is a configuration languange, and you create a configuration file, how does lua apply the new configuration to the original program it is extending?'
> thanks...
>
>
>
Lua does this by calling functions in the C, C++ etc. side of the
application.
-Alex
End of Lua Digest, Vol 16, Issue 3
~**********************************
