• Diggory (3/3) May 04 2013 I'm trying to test using a "static if" statement if a tuple of
• Simen Kjaeraas (4/6) May 04 2013 http://dlang.org/phobos/std_typetuple#.staticIndexOf
• Diggory (2/7) May 04 2013 It's not a TypeTuple, it's a tuple of strings.
• bearophile (6/7) May 04 2013 Then one simple way to do it is to convert it into an array of
• Diggory (6/13) May 04 2013 OK, that makes sense but I'm not sure I understand that syntax.
• bearophile (10/12) May 04 2013 Nope. You have to extract the inherent typetuple first. And this
• Diggory (8/20) May 04 2013 Is the behaviour of the empty [] when applied to tuples
• bearophile (8/15) May 05 2013 I see. Then a good idea is to create a little function, to solve

"Diggory" <diggsey googlemail.com> writes:

I'm trying to test using a "static if" statement if a tuple of 
strings contains a particular string. What's the easiest/best way 
to do this?

"Simen Kjaeraas" <simen.kjaras gmail.com> writes:

On 2013-05-05, 01:42, Diggory wrote:

 I'm trying to test using a "static if" statement if a tuple of strings  
 contains a particular string. What's the easiest/best way to do this?



-- 
Simen

"Diggory" <diggsey googlemail.com> writes:

On Sunday, 5 May 2013 at 00:10:27 UTC, Simen Kjaeraas wrote:
 On 2013-05-05, 01:42, Diggory wrote:

 I'm trying to test using a "static if" statement if a tuple of 
 strings contains a particular string. What's the easiest/best 
 way to do this?



It's not a TypeTuple, it's a tuple of strings.

"bearophile" <bearophileHUGS lycos.com> writes:

Diggory:

 It's not a TypeTuple, it's a tuple of strings.

Then one simple way to do it is to convert it into an array of 
strings, and then use canFind:

[mytuple[]].canFind(needle)

Bye,
bearophile

"Diggory" <diggsey googlemail.com> writes:

On Sunday, 5 May 2013 at 00:33:34 UTC, bearophile wrote:
 Diggory:

 It's not a TypeTuple, it's a tuple of strings.

 Then one simple way to do it is to convert it into an array of 
 strings, and then use canFind:

 [mytuple[]].canFind(needle)

 Bye,
 bearophile

OK, that makes sense but I'm not sure I understand that syntax.

The documentation seems too say that "[mytuple]" will make an 
array, or that "mytuple[]" will make a slice from a tuple 
(presumably with no arguments it will slice the entire tuple?), 
so how does "[mytuple[]]" work?

"bearophile" <bearophileHUGS lycos.com> writes:

Diggory:

 The documentation seems too say that "[mytuple]" will make an 
 array,

Nope. You have to extract the inherent typetuple first. And this 
is what the [] syntax does (tested):


import std.stdio, std.typecons, std.algorithm;
void main() {
     auto t = tuple("foo", "bar", "spam");
     assert([t[]].canFind("bar"));
}

Bye,
bearophile

"Diggory" <diggsey googlemail.com> writes:

On Sunday, 5 May 2013 at 01:44:19 UTC, bearophile wrote:
 Diggory:

 The documentation seems too say that "[mytuple]" will make an 
 array,

 Nope. You have to extract the inherent typetuple first. And 
 this is what the [] syntax does (tested):


 import std.stdio, std.typecons, std.algorithm;
 void main() {
     auto t = tuple("foo", "bar", "spam");
     assert([t[]].canFind("bar"));
 }

 Bye,
 bearophile

Is the behaviour of the empty [] when applied to tuples 
documented anywhere?

The problem is that this doesn't work if the tuple is empty:
Error: template std.algorithm.canFind does not match any function 
template declaration.

And unfortunately in the situation I need it for an empty tuple 
is one of the most likely scenarios.

"bearophile" <bearophileHUGS lycos.com> writes:

Diggory:

 Is the behaviour of the empty [] when applied to tuples 
 documented anywhere?

I don't remember.


 The problem is that this doesn't work if the tuple is empty:
 Error: template std.algorithm.canFind does not match any 
 function template declaration.

 And unfortunately in the situation I need it for an empty tuple 
 is one of the most likely scenarios.

I see. Then a good idea is to create a little function, to solve 
this. It should contain a static if that tests for the empty 
tuple and returns false in that case, and otherwise uses the 
canFind.

Bye,
bearophile