Re: Can we deprecate "D-style Variadic Functions"
On Friday, 27 March 2015 at 20:57:51 UTC, Freddy wrote: template VariadicFunction(alias Imp){ auto VariadicFunction(T...)(T args){ void* data=&args; TypeInfo[T.length] rtti; foreach(i,type;T){ rtti[i]=typeid(type); } Imp(data,rtti); } } ``` I haven't looked in dmd's source yet but doesn't the compiler have to do (an inlined version of) this anyway for runtime variadic functions.
Re: Can we deprecate "D-style Variadic Functions"
On Friday, 27 March 2015 at 19:59:13 UTC, deadalnix wrote: To be fair, this is most likely going to be inlined an ditched away with any decent optimizer. It wouldn't even need alloca if sizeof and address of worked with tuples. ``` template VariadicFunction(alias Imp){ auto VariadicFunction(T...)(T args){ void* data=&args; TypeInfo[T.length] rtti; foreach(i,type;T){ rtti[i]=typeid(type); } Imp(data,rtti); } } ```
Re: Can we deprecate "D-style Variadic Functions"
On Friday, 27 March 2015 at 14:24:47 UTC, Shammah Chancellor wrote: On 2015-03-26 01:04:03 +, Freddy said: On Thursday, 26 March 2015 at 00:11:05 UTC, Dicebot wrote: On Wednesday, 25 March 2015 at 22:12:04 UTC, Freddy wrote: "D-style Variadic Functions" found here:http://dlang.org/function.html seem entirely out classed by Variadic Function Templates. Can we deprecate them? Those are two different concepts with different trade-offs. Using variadic templates adds template bloat. Using D-style variadics requires RTTI (and small overhead for it). It is up to library/application writer to decide what is best in his case. My ploblem is that Variadic Function shouldn't be builtin the language. They are rarely need and can be abstracted into a library. Something like this: ``` import core.stdc.stdlib: alloca; import std.stdio; template VariadicFunction(alias Imp){ auto VariadicFunction(T...)(T args){ enum size=T.length * TypeInfo.sizeof; auto rtti=cast(TypeInfo[])(alloca(size)[0..size]); foreach(i,type;T){ rtti[i]=typeid(type); } //auto data=&args; bug? doesn't work void* data; { size_t datasize;//T.sizeof doesn't work foreach(type;T){ datasize+=type.sizeof; } data=alloca(datasize); size_t inc; foreach(v;args){ *cast(typeof(v)*)(data+inc)=v; inc+=v.sizeof; } } Imp(data,rtti); } } private void rtVariadicImp(void* vars,scope const TypeInfo[] rtinfo){ writeln(*cast(int*)vars); writeln(rtinfo); } alias rtVariadic=VariadicFunction!(rtVariadicImp); void main(){ rtVariadic(1,'a'); } ``` I disagree, and your example does not get rid of the template bloat. That does in fact instantiate a template for every set of argument types. -Shammah To be fair, this is most likely going to be inlined an ditched away with any decent optimizer.
Re: Can we deprecate "D-style Variadic Functions"
What Shammah has said. Your proposal is not a proper replacement, it has very different effect on a binary. It could be possible to reimplement D-style varargs on top of C-style varargs + manual RTTI usage but not with template variadics.
Re: Can we deprecate "D-style Variadic Functions"
On 2015-03-26 01:04:03 +, Freddy said: On Thursday, 26 March 2015 at 00:11:05 UTC, Dicebot wrote: On Wednesday, 25 March 2015 at 22:12:04 UTC, Freddy wrote: "D-style Variadic Functions" found here:http://dlang.org/function.html seem entirely out classed by Variadic Function Templates. Can we deprecate them? Those are two different concepts with different trade-offs. Using variadic templates adds template bloat. Using D-style variadics requires RTTI (and small overhead for it). It is up to library/application writer to decide what is best in his case. My ploblem is that Variadic Function shouldn't be builtin the language. They are rarely need and can be abstracted into a library. Something like this: ``` import core.stdc.stdlib: alloca; import std.stdio; template VariadicFunction(alias Imp){ auto VariadicFunction(T...)(T args){ enum size=T.length * TypeInfo.sizeof; auto rtti=cast(TypeInfo[])(alloca(size)[0..size]); foreach(i,type;T){ rtti[i]=typeid(type); } //auto data=&args; bug? doesn't work void* data; { size_t datasize;//T.sizeof doesn't work foreach(type;T){ datasize+=type.sizeof; } data=alloca(datasize); size_t inc; foreach(v;args){ *cast(typeof(v)*)(data+inc)=v; inc+=v.sizeof; } } Imp(data,rtti); } } private void rtVariadicImp(void* vars,scope const TypeInfo[] rtinfo){ writeln(*cast(int*)vars); writeln(rtinfo); } alias rtVariadic=VariadicFunction!(rtVariadicImp); void main(){ rtVariadic(1,'a'); } ``` I disagree, and your example does not get rid of the template bloat. That does in fact instantiate a template for every set of argument types. -Shammah
Re: Can we deprecate "D-style Variadic Functions"
On Thursday, 26 March 2015 at 00:11:05 UTC, Dicebot wrote: On Wednesday, 25 March 2015 at 22:12:04 UTC, Freddy wrote: "D-style Variadic Functions" found here:http://dlang.org/function.html seem entirely out classed by Variadic Function Templates. Can we deprecate them? Those are two different concepts with different trade-offs. Using variadic templates adds template bloat. Using D-style variadics requires RTTI (and small overhead for it). It is up to library/application writer to decide what is best in his case. My ploblem is that Variadic Function shouldn't be builtin the language. They are rarely need and can be abstracted into a library. Something like this: ``` import core.stdc.stdlib: alloca; import std.stdio; template VariadicFunction(alias Imp){ auto VariadicFunction(T...)(T args){ enum size=T.length * TypeInfo.sizeof; auto rtti=cast(TypeInfo[])(alloca(size)[0..size]); foreach(i,type;T){ rtti[i]=typeid(type); } //auto data=&args; bug? doesn't work void* data; { size_t datasize;//T.sizeof doesn't work foreach(type;T){ datasize+=type.sizeof; } data=alloca(datasize); size_t inc; foreach(v;args){ *cast(typeof(v)*)(data+inc)=v; inc+=v.sizeof; } } Imp(data,rtti); } } private void rtVariadicImp(void* vars,scope const TypeInfo[] rtinfo){ writeln(*cast(int*)vars); writeln(rtinfo); } alias rtVariadic=VariadicFunction!(rtVariadicImp); void main(){ rtVariadic(1,'a'); } ```
Re: Can we deprecate "D-style Variadic Functions"
On Wednesday, 25 March 2015 at 22:12:04 UTC, Freddy wrote: "D-style Variadic Functions" found here:http://dlang.org/function.html seem entirely out classed by Variadic Function Templates. Can we deprecate them? Those are two different concepts with different trade-offs. Using variadic templates adds template bloat. Using D-style variadics requires RTTI (and small overhead for it). It is up to library/application writer to decide what is best in his case.
Re: Can we deprecate "D-style Variadic Functions"
On Wednesday, 25 March 2015 at 22:12:04 UTC, Freddy wrote: "D-style Variadic Functions" found here:http://dlang.org/function.html seem entirely out classed by Variadic Function Templates. Can we deprecate them? Surely you mean they are classed out by Typesafe Variadic Functions? Variadic Function Templates is a different thing used for a slightly different purpose...
Can we deprecate "D-style Variadic Functions"
"D-style Variadic Functions" found here:http://dlang.org/function.html seem entirely out classed by Variadic Function Templates. Can we deprecate them?