The new std.process is ready for review

[H. S. Teoh]

On Wed, Mar 13, 2013 at 09:43:59PM +0100, Lars T. Kyllingstad wrote:
> On Wednesday, 13 March 2013 at 20:26:44 UTC, Steven Schveighoffer
> wrote:
[...]
> >But with something similar to Dennis' idea, we have a possible way to
> >do that without making a copy of the current environment into an AA
> >and adding:
> >
> >struct EnvironmentArg
> >{
> >     this(string[string] env, bool useParent=false) { this.env =
> >env;
> >this.useParent = useParent;}
> >     this(bool useParent) {this.useParent = useParent;}
> >     string[string] env;
> >     bool useParent;
> >}
> >
> >spawnProcess("helloworld", EnvironmentArg(["x":"y"], true)); // use parent
> >environment, add x=y
> >spawnProcess("helloworld", EnvironmentArg(["x":"y"])); // replace environment with x=y
> >spawnProcess("helloworld", EnvironmentArg(false)); // use empty environment
> >spawnProcess("helloworld", EnvironmentArg(true)); // use parent environment exactly
> >
> >EnvironmentArg should probably have better name, and I would
> >recommend some global functions that make common things, like:
> >
> >EnvironmentArg emptyEnvironment() { return EnvironmentArg(null, false);}
> >EnvironmentArg parentEnvironment() { return EnvironmentArg(null, true);}
> >
> >Like? Hate?
> 
> Hmm.. what if spawnProcess() takes a normal string[string] like it
> does now, but we add a flag to Config that determines whether it is
> merged with the parent's environment or not?
> 
> string[string] myEnv = [ "foo" : "bar" ];
> spawnProcess("helloworld", null);     // Parent's env
> spawnProcess("helloworld", myEnv);    // Parent's env + myEnv
> spawnProcess("helloworld", null, ..., Config.clearEnv);  // Empty env
> spawnProcess("helloworld", myEnv, ..., Config.clearEnv); // Only myEnv
[...]

+1. I like this idea. Makes code more self-documenting, which is a good
thing.

Alternatively:

	struct useParentEnv { string[string] aa; }
	struct newEnv { string[string] aa; }

	spawnProcess(E)(string program, E env, ...) {
		static if (is(E == useParentEnv))
			// inherit values from current environment
		else
			// don't inherit from current environment
	}

	spawnProcess("helloworld", useParentEnv(["a": "b", ... ]), ...);
	spawnProcess("helloworld", newEnv(["a": "b", ... ]), ...);

Of course, rename useParentEnv and newEnv to something more suitable.


T

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