Re: Implicit conversion of struct to bool for if (s) operation ?
On Tuesday, 7 June 2016 at 22:28:57 UTC, Steven Schveighoffer wrote: It's news to me that while opCast for all other types is for explicit casting, opCast for bool works for implicit casting. as ag0... mentioned in another thread, opCast is NOT implicitly being invoked here, but rather explicitly. That is: bool x = someStruct; // error if(someStruct) // explicit opCast!bool Documented under 'Boolean Operations' at http://dlang.org/spec/operatoroverloading.html#cast
Re: Implicit conversion of struct to bool for if (s) operation ?
On 6/7/16 6:15 PM, Ali Çehreli wrote:
On 06/06/2016 08:28 AM, Adam D. Ruppe wrote:
On Monday, 6 June 2016 at 15:23:50 UTC, chmike wrote:
I would like an implicit conversion of Info to bool that return false
if category_ is null so that I can write
add:
bool opCast(T : bool)() {
return whatever;
}
to the struct and it should work.
It's news to me that while opCast for all other types is for explicit
casting, opCast for bool works for implicit casting.
as ag0... mentioned in another thread, opCast is NOT implicitly being
invoked here, but rather explicitly.
That is:
bool x = someStruct; // error
if(someStruct) // explicit opCast!bool
-Steve
Re: Implicit conversion of struct to bool for if (s) operation ?
On 06/06/2016 08:28 AM, Adam D. Ruppe wrote:
On Monday, 6 June 2016 at 15:23:50 UTC, chmike wrote:
I would like an implicit conversion of Info to bool that return false
if category_ is null so that I can write
add:
bool opCast(T : bool)() {
return whatever;
}
to the struct and it should work.
It's news to me that while opCast for all other types is for explicit
casting, opCast for bool works for implicit casting.
Ali
Re: Implicit conversion of struct to bool for if (s) operation ?
On Monday, 6 June 2016 at 15:34:18 UTC, chmike wrote:
On Monday, 6 June 2016 at 15:28:35 UTC, John wrote:
Thank you John and Adam. That was a quick answer !
Too late but another option would have been to put an alias this
on a bool getter:
struct Info
{
bool getStuff()
{
return true;
}
alias getStuff this;
}
Re: Implicit conversion of struct to bool for if (s) operation ?
On Monday, 6 June 2016 at 15:28:35 UTC, John wrote: Thank you John and Adam. That was a quick answer !
Re: Implicit conversion of struct to bool for if (s) operation ?
On Monday, 6 June 2016 at 15:23:50 UTC, chmike wrote:
I would like an implicit conversion of Info to bool that return
false if category_ is null so that I can write
add:
bool opCast(T : bool)() {
return whatever;
}
to the struct and it should work.
Re: Implicit conversion of struct to bool for if (s) operation ?
On Monday, 6 June 2016 at 15:23:50 UTC, chmike wrote:
Hello,
I have a structure with two fields ad defined as
struct Info {
this(int value, Category category)
{
category_ = category;
value_ = category ? value : 0;
}
// This converts implicitly to bool.
T opCast(T : bool)() {
return category_ !is null;
}
...
private:
Category category_ = null;
int value_ = 0;
}
I would like an implicit conversion of Info to bool that return
false if category_ is null so that I can write
Info s = foo();
if (s) {
...
}
and where
Info s2;
assert(!s2);
See the inserted code above.
