require("|D|filename") doesn't work in 2012.8.1

Magnusviri · August 2012

I use to be able to use require("|D|filename") but I just upgraded from 2012.2 (something) to 2012.8.1 and now it doesn't work. Does anyone know what has changed?

chipster123 · August 2012

I don't use the require but do use 'dofile('|D|filename) and that still works.

atilim · August 2012

I haven't tested on 2012.2.x yet but it shouldn't work on it either.

require searches for a Lua loader using the path stored in package.path. If you want, you can change it so that it doesn't prepend "./" in front of module name:

local file = io.open("|D|test.lua", "w")
file:write([[
	for i=1,4 do
		print("hello", i)
	end
]])
file:close()
 
print("original package.path", package.path)
package.path = "?.lua"
require("|D|test")

Magnusviri · August 2012

package.path = "?.lua" did the trick! Thanks!

alexzheng · August 2012

Is there any side effects by just changing the package.path to "?.lua" ?

Is that means we can download any lua file from the network and save it in the |D| direcory and excute it?

atilim · August 2012

Is there any side effects by just changing the package.path to "?.lua" ?

There isn't any side effects.

Is that means we can download any lua file from the network and save it in the |D| direcory and excute it?

Although you can (technically), Apple simply doesn't allow this.

alexzheng · August 2012

if I understand the package.path as something like the PATH env in the OS,should not be append the "?.lua" to package.path, not just repalce it?

atilim · August 2012

Exactly. And as a side note, it's only used by require command and nothing else. If you want, there are plenty of information here http://www.lua.org/manual/5.1/manual.html (search for package.path)

techdojo · August 2012

FWIW - Use of dofile() could get your app rejected by Apple. They do not allow "local" or downloaded code / scripts to be parsed / executed. Could lead to all sorts of nasty issues so there's a blanket stop on it

alexzheng · August 2012

Thanks All, I get it now.

Magnusviri · August 2012

I use this stuff for development only. When I have an app that I'm ready to put on the store I'll remove all of the dofile/require statements.

chipster123 · August 2012

FWIW - Use of dofile() could get your app rejected by Apple. They do not allow "local" or downloaded code / scripts to be parsed / executed. Could lead to all sorts of nasty issues so there's a blanket stop on it

So, it's OK to save and read text files line by line to |D| using read and write but not to use do file()?

Magnusviri · August 2012

Yeah, actually I was thinking about this and I realized that I'm building my game with dofile in mind. I'm wondering if I'm going to have to change that.

And one of my first concerns with Lua was its ability to execute code from anywhere. I think it is also possible to read a text file using the io library and then execute it. I'm not sure though.

Magnusviri · August 2012

To execute a string use loadstring(). It would be interesting to see if Apple denies any apps that use loadstring(), loadfile(), dofile(), or require().

http://www.lua.org/pil/8.html

OZApps · August 2012

I guess as long as you are not downloading any text (script) or bytecode from anywhere and then executing that using the dofile, Apple should not have an issue. However, other frameworks have sandboxed the loadstring, dofile and loadfile and thereby gotten a blanket approval for that framework. It is strange that Apple encourages that images and assets are downloaded by the app from a website to keep the app slim, but when a developer wants to download some levels, etc (scripts) and they do not allow that, instead encourage updates that take time to review, can be large in terms of size (20+ MB for updates, no delta patches/updates). Well, that is how it is, they call the shots and since we want to play in that playground, we have to abide by their rules.

Lastly, Apple is not a single entity, but a group of reviewers, some with more common sense than some others. Some more lax than others, so you will see all sort of things happen on the App store. One app with a particular feature will get approved and you might be in strife with a reviewer over the same feature.

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