Passing function(whose parameter would be dynamic and the type is unknown) as a parameter to another function.

[vino.B]

On Monday, 9 July 2018 at 15:49:50 UTC, Alex wrote:
> On Monday, 9 July 2018 at 15:40:53 UTC, vino.B wrote:
>> On Sunday, 8 July 2018 at 19:10:24 UTC, Alex wrote:
>>> On Sunday, 8 July 2018 at 18:46:31 UTC, vino.B wrote:
>>>>  Request you help, in the below code we pass the function 
>>>> "Testfun" as a parameter to another function "process" in 
>>>> order for the function "process" to work we have to specify 
>>>> the type of the parameter that is passed to the function "(T 
>>>> function(string, int) coRoutine, string Test, int Size) ", 
>>>> so now how do we pass a function whose parameter would be 
>>>> dynamic and the type is unknown.
>>>
>>> What do you mean with a "function with dynamic parameters" 
>>> and "unknown type"?
>>>
>>> But how about
>>>
>>> ´´´
>>> void main()
>>> {
>>> 	process!fun();
>>> }
>>>
>>> void process(alias coRoutine, T...)(T params)
>>> {
>>> 	coRoutine(params);
>>> }
>>>
>>> auto fun(T...)(T params)
>>> {
>>>
>>> }
>>> ´´´
>>
>> HI Alex,
>>
>>  I tried you method, but it not working as expected, the 
>> process!fun1(Test1) works but the process!fun2(Test1, Size ) 
>> does not work, instead of displaying the value (Test, 1) it 
>> output's the parameter "Test1".
>>
>> Output:
>> Test
>> Test1
>>
>> If I comment process!fun1(Test1); then the output is same
>>
>> Output :
>> Test1
>>
>> import std.stdio: writeln;
>>
>>
>> void main()
>> {
>>     string Test1 = "Test";
>>     int Size = 1;
>>     process!fun1(Test1);
>>     process!fun2(Test1, Size );
>> }
>>
>> void process(alias coRoutine, T...)(T params)
>> {
>> 	coRoutine(params);
>> }
>>
>> auto fun1(T...)(T params)
>> {
>>    writeln(params);
>> }
>>
>> auto fun2(T...)(T params)
>> {
>>    writeln(params);
>> }
>>
>> From,
>> Vino.B
>
> As I can see, this is the expected output.
> The "1" after "Test" is the value of parameter "Size"...

Hi Alex,

  Thank you a lot, i was able to improvise using your logic, and i 
need more help, the below code is working as expected using your 
logic, now how do i get the return type of the function

Request Help:
void process(alias coRoutine, T...)(Array!string Dirlst, T params)
{
       ReturnType!coRoutine rData;   ///// This line is not working
       alias scRType = typeof(coRoutine(string.init, T.init));
       auto PFresult = taskPool.workerLocalStorage!scRType();
       foreach (string FFs; parallel(Dirlst[],1)) { PFresult.get 
~= coRoutine(FFs, params); }
       foreach(i; PFresult.toRange) { rData ~= i[][]; }
}

Error:
test.d(206): Error: template instance 
`std.traits.ReturnType!(coAgedDirClean)` does not match template 
declaration ReturnType(func...) if (func.length == 1 && 
isCallable!func)


Working Code:
auto coAgedDirClean(T...)(string FFs, T params)  {
      auto dFiles = Array!(Tuple!(string, 
SysTime))(dirEntries(FFs, SpanMode.shallow).filter!(a => a.isFile 
&& a.size > params[0]).map!(a => tuple(a.name, 
a.timeLastModified)));
      return dFiles;
}

auto coAgedDirDelete(T...)(string FFs, T params)  {
      auto dFiles = Array!(Tuple!(string, 
SysTime))(dirEntries(FFs, SpanMode.shallow).filter!(a => a.isFile 
&& a.size > params[0]).map!(a => tuple(a.name, 
a.timeLastModified)));
      if (params[1] == "run" && !dFiles.empty) {  foreach(d; 
parallel(dFiles[], 1)) { remove(d[0]); }}
      return dFiles;
}

void process(alias coRoutine, T...)(Array!string Dirlst, T params)
{
       alias scRType = typeof(coRoutine(string.init, T.init));
       auto PFresult = taskPool.workerLocalStorage!scRType();
       foreach (string FFs; parallel(Dirlst[],1)) { PFresult.get 
~= coRoutine(FFs, params); }
       foreach(i; PFresult.toRange) { writeln(i[][]); }
}

void main()
{
     Array!string AgedDir, DeleteDir;
     AgedDir.insert("C:\\Temp\\TEAM1");
     DeleteDir.insert("C:\\Temp\\BACKUP1");
     ulong Size = 102;
     string Step = "run";
     process!coAgedDirClean(AgedDir, Size );
     process!coAgedDirDelete(DeleteDir, Size, Step);
}

From,
Vino.B