• seany (19/19) Dec 06 2013 I have the following
• H. S. Teoh (20/42) Dec 06 2013 [...]
• seany (3/3) Dec 06 2013 why do i need the static? (is that not supposed to prevent
• Dicebot (7/10) Dec 06 2013 You can possibly use normal if but most likely you will get
• Jesse Phillips (4/7) Dec 06 2013 'static if' means check this at compile time, which happens to

"seany" <seany uni-bonn.de> writes:

I have the following

void functionName(T)(T argumentVar)
{

     /+
     now i want that based on type of argumentVar, things will be 
done
     eg :
     if there is a function gettype; then :
     +/

     switch(argumentVar.gettype)
     {
         case "string array":
              //do something
         case "string":
              //treat srting as a file...
              //then do some other things
     }

}


How do I incorporrate this?

"H. S. Teoh" <hsteoh quickfur.ath.cx> writes:

On Fri, Dec 06, 2013 at 09:18:51PM +0100, seany wrote:
 I have the following
 
 void functionName(T)(T argumentVar)
 {
 
     /+
     now i want that based on type of argumentVar, things will be
 done
     eg :
     if there is a function gettype; then :
     +/
 
     switch(argumentVar.gettype)
     {
         case "string array":
              //do something
         case "string":
              //treat srting as a file...
              //then do some other things
     }
 
 }

[...]

Use static if and an is-expression:

	static if (is(T == string[]))
		// handle string arrays
	else static if (is(T == string))
		// handle strings
	else static assert(0);	// this is a good idea to catch bugs,
				// if somebody passes in a type that
				// isn't supported

Depending on your application, you may want to use the more permissive
is(X : Y) syntax instead. The ':' means "if X can implicitly convert to
Y", whereas the is(X == Y) syntax means "if X is exactly the same type
as Y". So if you want to accept both string and char[], you'd write:

	static if (is(T : const(char)[]))
		// handles string, char[], and const(char)[]

since both unqualified and immutable can implicitly convert to const.


T

-- 
Unix is my IDE. -- Justin Whear

"seany" <seany uni-bonn.de> writes:

why do i need the static? (is that not supposed to prevent 
insertations of new scopes inside the braces? is it really 
needed?)

"Dicebot" <public dicebot.lv> writes:

On Friday, 6 December 2013 at 20:58:15 UTC, seany wrote:
 why do i need the static? (is that not supposed to prevent 
 insertations of new scopes inside the braces? is it really 
 needed?)

You can possibly use normal if but most likely you will get 
compilation errors from other conditional branches as they will 
use parameter type in semantically incorrect way. `static if` 
avoids compilation of not matching blocks and does not have this 
issue. You can explicitly define new scope using one extra pair 
of braces if you want it.

"Jesse Phillips" <Jesse.K.Phillips+D gmail.com> writes:

On Friday, 6 December 2013 at 20:58:15 UTC, seany wrote:
 why do i need the static? (is that not supposed to prevent 
 insertations of new scopes inside the braces? is it really 
 needed?)

'static if' means check this at compile time, which happens to 
not introduce a new scope, because otherwise it wouldn't be very 
useful.