Re: Template bug with second mixin?
thanks a lot. That makes sense.
Kind regards
André
On Friday, 5 December 2014 at 09:29:21 UTC, ketmar via
Digitalmars-d-learn wrote:
On Fri, 05 Dec 2014 09:19:27 +
Andre via Digitalmars-d-learn
wrote:
I think I mimized the coding too much.
What I actually want to achieve is to generate read methods
in the structure for different data types (Ubyte, short, int):
I thought the eponymous trick would insert the content of the
enum instead the name itself?
string getReadMethods(string methodName, string dataType)
{
return dataType~` `~methodName~`(size_t idx) {
return v_arr[idx].get!`~dataType~`; }`;
}
template insertReadMethods(string MethodName, DataType)
{
enum insertReadMethods = getReadMethods(MethodName,
DataType.stringof);
}
struct Data
{
mixin insertReadMethods!("readTinyInt", ubyte);
mixin insertReadMethods!("readShortInt", short);
}
void main(){}
you musunderstood how mixin templates works. mixin templates
are more
like macroses than templates per se, so you don't need to assign
anything to enum to get the result. i.e.
string getReadMethods(string methodName, string dataType)
{
return dataType~` `~methodName~`(size_t idx) {
return v_arr[idx].get!`~dataType~`; }`;
}
template insertReadMethods(string MethodName, DataType)
{
/*enum insertReadMethods =*/ // no need to do this
// do that instead ;-)
mixin(getReadMethods(MethodName, DataType.stringof));
}
struct Data
{
mixin insertReadMethods!("readTinyInt", ubyte);
mixin insertReadMethods!("readShortInt", short);
}
think about mixin templates as macro definitions which will be
just
inserted where you instantiated them.
Re: Template bug with second mixin?
On Fri, 05 Dec 2014 09:19:27 +
Andre via Digitalmars-d-learn wrote:
> I think I mimized the coding too much.
> What I actually want to achieve is to generate read methods
> in the structure for different data types (Ubyte, short, int):
>
> I thought the eponymous trick would insert the content of the
> enum instead the name itself?
>
> string getReadMethods(string methodName, string dataType)
> {
>return dataType~` `~methodName~`(size_t idx) {
> return v_arr[idx].get!`~dataType~`; }`;
> }
>
> template insertReadMethods(string MethodName, DataType)
> {
>enum insertReadMethods = getReadMethods(MethodName,
> DataType.stringof);
> }
>
> struct Data
> {
> mixin insertReadMethods!("readTinyInt", ubyte);
> mixin insertReadMethods!("readShortInt", short);
> }
>
> void main(){}
you musunderstood how mixin templates works. mixin templates are more
like macroses than templates per se, so you don't need to assign
anything to enum to get the result. i.e.
string getReadMethods(string methodName, string dataType)
{
return dataType~` `~methodName~`(size_t idx) {
return v_arr[idx].get!`~dataType~`; }`;
}
template insertReadMethods(string MethodName, DataType)
{
/*enum insertReadMethods =*/ // no need to do this
// do that instead ;-)
mixin(getReadMethods(MethodName, DataType.stringof));
}
struct Data
{
mixin insertReadMethods!("readTinyInt", ubyte);
mixin insertReadMethods!("readShortInt", short);
}
think about mixin templates as macro definitions which will be just
inserted where you instantiated them.
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Re: Template bug with second mixin?
I think I mimized the coding too much.
What I actually want to achieve is to generate read methods
in the structure for different data types (Ubyte, short, int):
I thought the eponymous trick would insert the content of the
enum instead the name itself?
string getReadMethods(string methodName, string dataType)
{
return dataType~` `~methodName~`(size_t idx) {
return v_arr[idx].get!`~dataType~`; }`;
}
template insertReadMethods(string MethodName, DataType)
{
enum insertReadMethods = getReadMethods(MethodName,
DataType.stringof);
}
struct Data
{
mixin insertReadMethods!("readTinyInt", ubyte);
mixin insertReadMethods!("readShortInt", short);
}
void main(){}
Kind regards
André
On Friday, 5 December 2014 at 07:28:26 UTC, ketmar via
Digitalmars-d-learn wrote:
On Fri, 05 Dec 2014 07:06:34 +
Andre via Digitalmars-d-learn
wrote:
Hi,
following coding fails to compile with 2.066.0 and
2.067.0-b1.
This is a bug, or?
source\app.d(9): Error: mixin
app.Data.insertReadMethods!("readTinyInt", ubyte)
is not defined
template insertReadMethods(string MethodName, DataType)
{
enum insertReadMethods = "";
}
struct Data
{
mixin insertReadMethods!("readTinyInt", ubyte);
mixin insertReadMethods!("readTinyInt", ubyte);
}
void main(){}
i.e. "mixin template" inserts it's names into the same scope,
and
compiler searching symbols from innermost scope up to module
scope.
here first mixin inserts 'enum' member, and searching for
second mixin
hits that enum member. to avoid things going out of control
compiler is
not trying to guess what you want but stops with error, giving
you a
chance to fix the code.
Re: Template bug with second mixin?
On Fri, 05 Dec 2014 07:06:34 +
Andre via Digitalmars-d-learn wrote:
> Hi,
>
> following coding fails to compile with 2.066.0 and
> 2.067.0-b1.
>
>
> This is a bug, or?
> source\app.d(9): Error: mixin
> app.Data.insertReadMethods!("readTinyInt", ubyte)
> is not defined
>
> template insertReadMethods(string MethodName, DataType)
> {
> enum insertReadMethods = "";
> }
>
> struct Data
> {
> mixin insertReadMethods!("readTinyInt", ubyte);
> mixin insertReadMethods!("readTinyInt", ubyte);
> }
>
> void main(){}
i.e. "mixin template" inserts it's names into the same scope, and
compiler searching symbols from innermost scope up to module scope.
here first mixin inserts 'enum' member, and searching for second mixin
hits that enum member. to avoid things going out of control compiler is
not trying to guess what you want but stops with error, giving you a
chance to fix the code.
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Re: Template bug with second mixin?
On Fri, 05 Dec 2014 07:06:34 +
Andre via Digitalmars-d-learn wrote:
> Hi,
>
> following coding fails to compile with 2.066.0 and
> 2.067.0-b1.
>
>
> This is a bug, or?
> source\app.d(9): Error: mixin
> app.Data.insertReadMethods!("readTinyInt", ubyte)
> is not defined
>
> template insertReadMethods(string MethodName, DataType)
> {
> enum insertReadMethods = "";
> }
>
> struct Data
> {
> mixin insertReadMethods!("readTinyInt", ubyte);
> mixin insertReadMethods!("readTinyInt", ubyte);
> }
>
> void main(){}
not a bug. what you doing is actually:
struct Data
{
enum insertReadMethods = "";
mixin insertReadMethods!("readTinyInt", ubyte);
}
`enum insertReadMethods` is definitely not a template, and compiler
correctly tells that to you.
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Template bug with second mixin?
Hi,
following coding fails to compile with 2.066.0 and
2.067.0-b1.
This is a bug, or?
source\app.d(9): Error: mixin
app.Data.insertReadMethods!("readTinyInt", ubyte)
is not defined
template insertReadMethods(string MethodName, DataType)
{
enum insertReadMethods = "";
}
struct Data
{
mixin insertReadMethods!("readTinyInt", ubyte);
mixin insertReadMethods!("readTinyInt", ubyte);
}
void main(){}
Kind regards
André
