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Subject: Re: [boost] Boost.Process article: Tutorial and request for comments
From: vicente.botet (vicente.botet_at_[hidden])
Date: 2009-04-25 13:25:09

----- Original Message -----
From: "Phil Endecott" <spam_from_boost_dev_at_[hidden]>
To: <boost_at_[hidden]>
Sent: Saturday, April 25, 2009 4:13 PM
Subject: Re: [boost] Boost.Process article: Tutorial and request for comments

> Boris Schaeling wrote:
>> On Tue, 21 Apr 2009 20:15:11 +0200, Phil Endecott wrote:
>>> Re the environment: I'm not enthusiastic that you have copied the
>>> environment into your own data structure. Why can't your environment
>>> type just wrap getenv() and setenv()? i.e.
>> The type environment is also used to setup a new environment for a child
>> process, eg.:
>> context ctx;
>> ctx.environment.insert(environment::value_type("PATH", "/newpath"));
>> launch(..., ctx);
> Typically I would write:
> fork();
> setenv("PATH","/newpath");
> exec();
> So the new child process gets the parent's environment with any new
> variables added or changed. This seems a lot simpler than copying the
> whole environment.

Yes, this seems much more efficient. So the Process library should use the environement filed as a list of environment variable to set on the child process.

>>> Why don't you boil it down to:
>>> launch_process("notepad.exe");
>> Currently the environment variables of the current process are not
>> automatically inherited by a child process. I agree that it should be
>> easier to launch a new process. But then environment variables should
>> probably be inherited by default?
> The environment is inherited across fork() and all those versions of
> exec() that don't explicitly set a new environment.

I agree that the default must inherit the environement variables, no need to state this explictly, not need to copy it.
>>>> it is very important to refer to the executable with an absolute path -
>>>> on all platforms including POSIX systems
>>> Why do you say that?
>> It's a requirement of Boost.Process. It doesn't need to be an absolute
>> path but can also be a relative path of course.
> Right, so it doesn't need to be an absolute path.
>> What's not guaranteed
>> though is that an executable is automatically found when only a filename
>> is given. There is a function which searches for an executable and returns
>> an absolute path. Would you like to see Boost.Process search for an
>> executable automatically?
> No, I'd like to see it use one of the versions of exec() that does this
> for you.

I agree again.


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