Future(s) for D.

[Etienne via Digitalmars-d]

On Monday, 22 June 2015 at 14:03:47 UTC, Laeeth Isharc wrote:
> On Monday, 22 June 2015 at 11:29:50 UTC, Jacob Carlborg wrote:
>> On 22/06/15 01:43, Nick Sabalausky wrote:
>>
>>> Curiosity, what libraries do you feel a lack of?
>>
>> For work, that would be:
>
>> * Some way to interface with Selenium and PhantomJS
>
> It's not pretty, but for what I want to do I have found 
> embedding Python calls to phantomjs code within a D program 
> works quite well.
>
> The SQLite stuff looks okay, although I haven't used for a big 
> project yet.

This is how I use it as a persistent storage for property 
get/setters. Takes some imagination at first, but it saves a huge 
amount of time/headaches on the long run.

/// Opens the SQLite database from the data folder. The user must 
call .close() when finished!
Database openDB(bool read = true) {
	// DB is always created in static ctor
	return Database(DATA_FOLDER_PATH() ~ "my.db", read ? 
SQLITE_OPEN_READONLY : (SQLITE_OPEN_READWRITE | 
SQLITE_OPEN_CREATE));
}


	private T get(T)(string name, lazy T default_value = T.init) {
		Database sqlite = openDB(READ);
		scope(exit) sqlite.close();
		T ret;
		try {
			auto results = sqlite.execute("SELECT value FROM config WHERE 
name='" ~ name ~ "';");
			auto val = results.oneValue!string;
			ret = val.to!T;
		}
		catch { ret = default_value; }
		return ret;
	}

	private void set(T)(string name, T value) {
		Database sqlite = openDB(WRITE);
		scope(exit) sqlite.close();
		bool exists;
		try {
			ResultRange res = sqlite.prepare("SELECT value FROM config 
WHERE name=?;").bind(1, name).execute();
			string val = res.oneValue!string; // will throw if the value 
is not there
			// Update the existing value.
			auto prep = sqlite.prepare("UPDATE TABLE config SET value=? 
WHERE name=?;").bind(1, name).execute();
			prep.bind(1, value.to!string);
			res = prep.execute();
		}
		catch {
			exists = false;
		}
		
		if (!exists) {
			auto res = sqlite.prepare("INSERT INTO config (name, value) 
VALUES (?, ?);").bind(1, name).bind(2, value.to!string).execute();
		}
	}

// usage:

	@property Duration created() {
		return get!ulong("created", 120).dur!"seconds";
	}

	@property void created(Duration val) {
		set("created", val.total!"seconds");
	}