• Suliman (47/47) Jan 01 2015 I need to pass some config to ddbc driver. When I use static
• Tobias Pankrath (4/10) Jan 01 2015 int does not implicitly convert to short. It does in the
• Suliman (4/4) Jan 01 2015 But why variant:
• Tobias Pankrath (7/11) Jan 01 2015 As I said the compiler infers that 5432 is between short.min and
• bearophile (6/10) Jan 01 2015 Because value range analysis now propagates the range even across
• =?UTF-8?B?QWxpIMOHZWhyZWxp?= (4/7) Jan 01 2015 Walter Bright explains the reasons in his "Value Range Propagation" arti...

"Suliman" <evermind live.ru> writes:

  I need to pass some config to ddbc driver. When I use static 
const all work ok.
static const string PGSQL_UNITTEST_HOST = "localhost";
static const int    PGSQL_UNITTEST_PORT = 5432;
static const string PGSQL_UNITTEST_USER = "postgres";
static const string PGSQL_UNITTEST_PASSWORD = "Infinity8";
static const string PGSQL_UNITTEST_DB = "test2";

But using static const mean that settings will be hardcoded. But 
I need to read it from config file.

So I need so simply declared it as:

this(parseConfig parseconfig)
{

string PGSQL_UNITTEST_HOST = parseconfig.dbhost; 	
int    PGSQL_UNITTEST_PORT = parseconfig.dbport; 	 	
string PGSQL_UNITTEST_USER = parseconfig.dbuser;
string PGSQL_UNITTEST_PASSWORD = parseconfig.dbpass;
string PGSQL_UNITTEST_DB = parseconfig.dbname;
...
}

But when I do it like above code stop compile and I am getting 
error:

source\app.d(218): Error: function 
ddbc.drivers.pgsqlddbc.PGSQLDriver.generateUrl (string host, 
ushort port, string dbname) is not callable using argument types  
(string, int, string)

I looked at driver source code and have found next code:

     class PGSQLDriver : Driver {
     	// helper function
     	public static string generateUrl(string host, ushort port, 
string dbname) {
     		return "postgresql://" ~ host ~ ":" ~ to!string(port) ~ "/" 
~ dbname;
     	}
     	public static string[string] setUserAndPassword(string 
username, string password) {
     		string[string] params;
     		params["user"] = username;
     		params["password"] = password;
     		params["ssl"] = "true";
     		return params;
     	}
		
So it's look like that it can accept strings and ints without 
problem.

And I really can't understand why it's accept only "static const 
string" constructions...
		

"Tobias Pankrath" <tobias pankrath.net> writes:

 		
 So it's look like that it can accept strings and ints without 
 problem.

 And I really can't understand why it's accept only "static 
 const string" constructions...
 		

int does not implicitly convert to short. It does in the 
hardcoded version, because the compiler can prove that the value 
is between short.min and short.max.

Use to!short() to convert it to short.

"Suliman" <evermind live.ru> writes:

But why variant:
static const int PGSQL_UNITTEST_PORT = 5432;

do not require of implicit convert to!short() at connection 
string?

"Tobias Pankrath" <tobias pankrath.net> writes:

On Thursday, 1 January 2015 at 13:09:21 UTC, Suliman wrote:
 But why variant:
 static const int PGSQL_UNITTEST_PORT = 5432;

 do not require of implicit convert to!short() at connection 
 string?

As I said the compiler infers that 5432 is between short.min and 
short.max. Try it with something out of this range.

BTW: If you just want to have a global constant, I'd use enum or 
immutable:

enum PGSQL_UNITTEST_PORT = 5432;
immutable PGSQL_UNITTEST_PORT = 5432;

"bearophile" <bearophileHUGS lycos.com> writes:

Suliman:

 But why variant:
 static const int PGSQL_UNITTEST_PORT = 5432;

 do not require of implicit convert to!short() at connection 
 string?

Because value range analysis now propagates the range even across 
expressions if they are const. It's a recent improvement to make 
the D compile a bit less stupid.

Bye,
bearophile

=?UTF-8?B?QWxpIMOHZWhyZWxp?= <acehreli yahoo.com> writes:

On 01/01/2015 05:09 AM, Suliman wrote:
 But why variant:
 static const int PGSQL_UNITTEST_PORT = 5432;

 do not require of implicit convert to!short() at connection string?

Walter Bright explains the reasons in his "Value Range Propagation" article:

   http://www.drdobbs.com/tools/value-range-propagation/229300211

Ali