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digitalmars.D.learn - Template substitution for function parameters

reply Nicholas Wilson <iamthewilsonator hotmail.com> writes:
So I have the following types

struct DevicePointer(T) { T* ptr; }

struct Buffer(T)
{
     void* driverObject;
     T[] hostMemory;
}

and a function

auto enqueue(alias k)(HostArgsOf!k) { ... }

where k would be a function like

void foo( DevicePointer!float a, float b , int c) { ... }

How can I write HostArgsOf such that HostArgsOf!foo yields:
AliasSeq!(Buffer!float, float, int)
preferably in such a way that I can add additional 
transformations to it later on?

i.e. it substitutes the template DevicePointer for the template 
Buffer in Parameters!foo,
The templates can be assumed to not be nested templates, i.e. 
DevicePointer!(DevicePointer!(float)) will never occur neither 
will Buffer!(Buffer!(float) or any cross templates)
Sep 01
next sibling parent reply user1234 <user1234 12.hu> writes:
On Friday, 1 September 2017 at 10:15:09 UTC, Nicholas Wilson 
wrote:
 So I have the following types
 ...
 i.e. it substitutes the template DevicePointer for the template 
 Buffer in Parameters!foo,
 The templates can be assumed to not be nested templates, i.e. 
 DevicePointer!(DevicePointer!(float)) will never occur neither 
 will Buffer!(Buffer!(float) or any cross templates)
Wow, this Question triggers an immediate headache...What about this ? import std.traits: Parameters; alias HostArgsOf(alias A) = AliasSeq!(Parameters!A[0], Parameters!A[1], Parameters!A[2]);
Sep 01
parent Nicholas Wilson <iamthewilsonator hotmail.com> writes:
On Friday, 1 September 2017 at 10:58:51 UTC, user1234 wrote:
 On Friday, 1 September 2017 at 10:15:09 UTC, Nicholas Wilson 
 wrote:
 So I have the following types
 ...
 i.e. it substitutes the template DevicePointer for the 
 template Buffer in Parameters!foo,
 The templates can be assumed to not be nested templates, i.e. 
 DevicePointer!(DevicePointer!(float)) will never occur neither 
 will Buffer!(Buffer!(float) or any cross templates)
Wow, this Question triggers an immediate headache...What about this ? import std.traits: Parameters; alias HostArgsOf(alias A) = AliasSeq!(Parameters!A[0], Parameters!A[1], Parameters!A[2]);
It will probably take the form alias HostArgsOf(alias k) = staticMap!(something, Parameters!k); I'm just not sure how to formulate the something.
Sep 01
prev sibling parent reply Biotronic <simen.kjaras gmail.com> writes:
On Friday, 1 September 2017 at 10:15:09 UTC, Nicholas Wilson 
wrote:
 So I have the following types

 struct DevicePointer(T) { T* ptr; }

 struct Buffer(T)
 {
     void* driverObject;
     T[] hostMemory;
 }

 and a function

 auto enqueue(alias k)(HostArgsOf!k) { ... }

 where k would be a function like

 void foo( DevicePointer!float a, float b , int c) { ... }

 How can I write HostArgsOf such that HostArgsOf!foo yields:
 AliasSeq!(Buffer!float, float, int)
 preferably in such a way that I can add additional 
 transformations to it later on?

 i.e. it substitutes the template DevicePointer for the template 
 Buffer in Parameters!foo,
 The templates can be assumed to not be nested templates, i.e. 
 DevicePointer!(DevicePointer!(float)) will never occur neither 
 will Buffer!(Buffer!(float) or any cross templates)
template k(alias fn) { import std.meta, std.traits; alias k = staticMap!(ReplaceTemplate!(DevicePointer, Buffer), Parameters!fn); } template ReplaceTemplate(alias needle, alias replacement) { template ReplaceTemplate(alias T) { static if (is(T : needle!Args, Args...)) { alias ReplaceTemplate = replacement!Args; } else { alias ReplaceTemplate = T; } } }
Sep 01
next sibling parent Nicholas Wilson <iamthewilsonator hotmail.com> writes:
On Friday, 1 September 2017 at 11:33:15 UTC, Biotronic wrote:
 On Friday, 1 September 2017 at 10:15:09 UTC, Nicholas Wilson 
 wrote:
 So I have the following types

 struct DevicePointer(T) { T* ptr; }

 struct Buffer(T)
 {
     void* driverObject;
     T[] hostMemory;
 }

 and a function

 auto enqueue(alias k)(HostArgsOf!k) { ... }

 where k would be a function like

 void foo( DevicePointer!float a, float b , int c) { ... }

 How can I write HostArgsOf such that HostArgsOf!foo yields:
 AliasSeq!(Buffer!float, float, int)
 preferably in such a way that I can add additional 
 transformations to it later on?

 i.e. it substitutes the template DevicePointer for the 
 template Buffer in Parameters!foo,
 The templates can be assumed to not be nested templates, i.e. 
 DevicePointer!(DevicePointer!(float)) will never occur neither 
 will Buffer!(Buffer!(float) or any cross templates)
template k(alias fn) { import std.meta, std.traits; alias k = staticMap!(ReplaceTemplate!(DevicePointer, Buffer), Parameters!fn); } template ReplaceTemplate(alias needle, alias replacement) { template ReplaceTemplate(alias T) { static if (is(T : needle!Args, Args...)) { alias ReplaceTemplate = replacement!Args; } else { alias ReplaceTemplate = T; } } }
Thanks!
Sep 01
prev sibling parent reply Nicholas Wilson <iamthewilsonator hotmail.com> writes:
On Friday, 1 September 2017 at 11:33:15 UTC, Biotronic wrote:
 On Friday, 1 September 2017 at 10:15:09 UTC, Nicholas Wilson 
 wrote:
 So I have the following types

 struct DevicePointer(T) { T* ptr; }

 struct Buffer(T)
 {
     void* driverObject;
     T[] hostMemory;
 }

 and a function

 auto enqueue(alias k)(HostArgsOf!k) { ... }

 where k would be a function like

 void foo( DevicePointer!float a, float b , int c) { ... }

 How can I write HostArgsOf such that HostArgsOf!foo yields:
 AliasSeq!(Buffer!float, float, int)
 preferably in such a way that I can add additional 
 transformations to it later on?

 i.e. it substitutes the template DevicePointer for the 
 template Buffer in Parameters!foo,
 The templates can be assumed to not be nested templates, i.e. 
 DevicePointer!(DevicePointer!(float)) will never occur neither 
 will Buffer!(Buffer!(float) or any cross templates)
template k(alias fn) { import std.meta, std.traits; alias k = staticMap!(ReplaceTemplate!(DevicePointer, Buffer), Parameters!fn); } template ReplaceTemplate(alias needle, alias replacement) { template ReplaceTemplate(alias T) { static if (is(T : needle!Args, Args...)) { alias ReplaceTemplate = replacement!Args; } else { alias ReplaceTemplate = T; } } }
Hmm, it seems I oversimplified the example a bit and this doesn't quite work for my actual usecase. struct DevicePointer(int n,T) { T* ptr; } alias GlobalPointer(T) = DevicePointer!(1,T); k!foo yields DevicePointer!(cast(AddrSpace)1u, float), float, int instead of Buffer!float, float, int I think because the is(T : needle!Args, Args...) fails.
Sep 01
parent Biotronic <simen.kjaras gmail.com> writes:
On Saturday, 2 September 2017 at 01:41:14 UTC, Nicholas Wilson 
wrote:
 On Friday, 1 September 2017 at 11:33:15 UTC, Biotronic wrote:
 On Friday, 1 September 2017 at 10:15:09 UTC, Nicholas Wilson 
 wrote:
 So I have the following types

 struct DevicePointer(T) { T* ptr; }

 struct Buffer(T)
 {
     void* driverObject;
     T[] hostMemory;
 }

 and a function

 auto enqueue(alias k)(HostArgsOf!k) { ... }

 where k would be a function like

 void foo( DevicePointer!float a, float b , int c) { ... }

 How can I write HostArgsOf such that HostArgsOf!foo yields:
 AliasSeq!(Buffer!float, float, int)
 preferably in such a way that I can add additional 
 transformations to it later on?

 i.e. it substitutes the template DevicePointer for the 
 template Buffer in Parameters!foo,
 The templates can be assumed to not be nested templates, i.e. 
 DevicePointer!(DevicePointer!(float)) will never occur 
 neither will Buffer!(Buffer!(float) or any cross templates)
template k(alias fn) { import std.meta, std.traits; alias k = staticMap!(ReplaceTemplate!(DevicePointer, Buffer), Parameters!fn); } template ReplaceTemplate(alias needle, alias replacement) { template ReplaceTemplate(alias T) { static if (is(T : needle!Args, Args...)) { alias ReplaceTemplate = replacement!Args; } else { alias ReplaceTemplate = T; } } }
Hmm, it seems I oversimplified the example a bit and this doesn't quite work for my actual usecase. struct DevicePointer(int n,T) { T* ptr; } alias GlobalPointer(T) = DevicePointer!(1,T); k!foo yields DevicePointer!(cast(AddrSpace)1u, float), float, int instead of Buffer!float, float, int I think because the is(T : needle!Args, Args...) fails.
It really shouldn't work at all - the is(T : ...) works great, but gives Args as (1, float), and fails to instantiate Buffer with those arguments. This should give a compilation error. Anyways, updated code that should work: template ReplaceTemplate(alias needle, alias replacement) { template ReplaceTemplate(alias T) { static if (is(T : needle!Args, Args...)) { alias ReplaceTemplate = replacement!(Args[1]); } else { alias ReplaceTemplate = T; } } } If you only ever use this for DevicePointer and Buffer, a less generic solution might be more understandable for maintainers: template ReplaceDevicePointer(alias T) { static if (is(T : DevicePointer!(n, T), int n, T)) { alias ReplaceDevicePointer = Buffer!T; } else { alias ReplaceDevicePointer = T; } } -- Biotronic
Sep 03