Re: catching Lua output

[Philipp Kraus <philipp.kraus@...>]

Am 02.12.2012 um 23:57 schrieb Tangent 128:

> On 12/02/2012 04:11 PM, Philipp Kraus wrote:
>> Am 02.12.2012 um 21:59 schrieb Tangent 128:
>> 
>>> <snip>
>>> You want to define your own print function, I think.
>>> 
>>> After you've opened any standard libraries into the Lua state, set the
>>> global "print" value to your custom function.
>>> 
>>> See lua_pushcfunction, lua_CFunction, and lua_setglobal in the docs.
>>> 
>>> (This would not intercept write()s from the io library, but I am
>>> guessing that that isn't used by simulation actors.)
>> can I catch also the io.write calls? I will add also my own "simulation package"
>> with some different function, so I can add my own print call, but on usability I
>> would like to catch the out (if I can), because some user will use the io.write
>> and the output is lost, if there is no catching
>> 
>> Phil
> 
> All the libraries are just functions kept in tables; you can replace any
> of them with your own versions before you let the user code run. You
> just need to write a replacement.
> 
> Depending on the application though, you may not need to provide the io
> library to the user scripts in the first place.
> 
> And there are two limited solutions that don't require custom functions
> at all:
> * if you don't otherwise use the stdout of your Lua-running process, you
> can use dup() and pipe() system calls to capture stdout directly.
> * you can use io.output(filename) to direct the io.write() function's
> output to a temporary file, and then send its contents back to the user
> afterwards.
> 
> -Joseph
> 


Great, thanks, this is perfect :-)

Phil