Mixin templates as virtual function add tool
Hi, I'm unfortunately in D this construction is not possible to
define:
class A(T){
abstract void method(S)(T arg1,S arg2);
}
As adding S to function declaration makes it not virtual.
But we can add this kind of functionality using mixin templates
mixin template BaseMix(T,S){
abstract void method(T arg1,S arg2);
}
class Base{
mixin BaseMix!(int,int);
}
//we can create now implementation by creation of other mixin
mixin template ImplMix(T,S){
override void method(T arg1,S arg2){
import std.stdio;
writeln(T.strinof," ",S.stringof);
//some dummy implementation
}
}
//and initiate the class
class Impl:Base{
mixin ImplMix!(int,int);
}
OK but i don't want to write each argument to mixin templates
invocations
like:
mixin ImplMix!(int,int);
mixin ImplMix!(int,byte);
mixin ImplMix!(int,string);
mixin ImplMix!(int,Object);
mixin ImplMix!(int,ubyte); etc.
It may produce a bug susceptible code as i would have to write it
in two class definitions.
I created template that automatically calls mixins with PList...
passed but i can't call it with mixins having more than one
template param like ImplMix(T,S)
template MixinTypeIterate(alias mixinTemplate,TList...){
static if(TList.length>0){
mixin mixinTemplate!(TList[0]);
static if(TList.length>1){
mixin MixinTypeIterate!(mixinTemplate,TList[1..$]);
}
}
}
how to alias mixin template to be able to pass it to this one ?
class BaseClass(T){
protected alias Types=AliasSeq!(int,string,ubyte);
private alias WrappedMix(S)=mixin Mix!(T,S); //not compiles -
mixins are no t regular templates
mixin MixinTypeIterate!(WrappedImplMix,Types);
}
class ImplClass(T){
private alias WrappedMix(T)=mixin ImplMix!(T,S); //not
compiles - mixins are no t regular templates
mixin MixinTypeIterate!(WrappedImplMix,Types);
}
How to make it work?
Joining AliasSeq/TypeTuple s
Hi, i want to join two or more tupples in to one, with mixing the
indexes like roundRobin but in compile time.
unittest{
import std.meta;
alias first=AliasSeq!(int, string,bool);
alias second=AliasSeq!("abc","def","ghi");
alias third=...
static assert(third==AliasSeq!(int, "abc", string, "def", bool,
"ghi"));
}
How to obtain this kind of functionality ? Is there maybe some
builin template for this in phobos ? I couldn't find this.
Thank you
Voitech.
Re: Variant.type bug ?
On Wednesday, 23 March 2016 at 19:18:50 UTC, Chris Wright wrote:
Consider the `coerce` method:
http://dpldocs.info/experimental-docs/std.variant.VariantN.coerce.html
Example:
import std.variant;
class A {}
class B : A {}
void main()
{
A b = new B;
auto bb = Variant(b).coerce!B;
assert (bb !is null);
}
Magnificent! Thank you ! :)
Re: Variant.type bug ?
On Wednesday, 23 March 2016 at 12:52:24 UTC, Adam D. Ruppe wrote:
On Wednesday, 23 March 2016 at 08:01:36 UTC, Voitech wrote:
Hi Variant stores variant.type as not the "highest" in
hierarchy.
Yeah, it stores the static type. You can use it to get that
then do a normal dynamic cast to test for a more derived type.
Ok but how to handle sittuation like this ?
class TypeHolder{
import std.variant;
Variant[TypeInfo] data;
void add(T)(T value){
data[typeid(value)]=value;
}
T getByType(T)(){
Variant retVar=data.get(typeid(T),Variant(null));
T val=retVar.get!T; //fails
return val;
}
}
unittest{
import std.variant;
A a= new A;
B b= new B;
C c = new C;
A ab= new B;
A ac = new C;
TypeHolder holder = new TypeHolder;
holder.add(a);
holder.add(ab);
holder.add(ac);
assert(holder.data.length==3);
A result=holder.getByType!A;
assert(result==a);
result=holder.getByType!B; //fails
assert(result==ab);
result=holder.getByType!C; //fails
assert(result==ac);
}
I can hold objects in other AA but Object[TypeInfo] rather than
Variant. Or is there a way to get super type of provided T ?
Variant.type bug ?
Hi Variant stores variant.type as not the "highest" in hierarchy.
Like this
A a= new A;
A b = new B; //B:A
Variant bVar=Variant(b);
bVar.type will be typeid(A) not typeid(B). Is this intentional ?
If so is there a way to get "concrete" type of "b" variable like
when passing to template function ?
void templateFunc(T)(T v){//just test function for B not used
with other type
import std.variant;
typeof(v) val=v;//concrete type ??
Variant var=val;
assert(var.type==typeid(B));//fails
}
unittest{
A b= new B;
templateFunc(b);
}
Types and unittests:
module typeTest;
import std.traits;
import std.meta;
class A{
void a(){}
}
class B:A{
int b(){
return 1;
}
}
class C:B,D{
string c(){
return "";
}
override int d() {
return 0;
}
}
interface D{
int d();
}
void templateFunc(T)(T v){//just test function for B not used
with other
import std.variant;
typeof(v) val=v;//concrete type ??
Variant var=val;
assert(var.type==typeid(B));//fails
}
unittest{
A b= new B;
templateFunc(b);
}
unittest{
import std.variant;
A a= new A;
B b= new B;
C c = new C;
A ab= new B;
A ac = new C;
Variant variant;
variant=a;
assert(typeid(a) == variant.type);
variant=b;
assert(typeid(b) == variant.type);
variant=c;
assert(typeid(c) == variant.type);
variant=ab;
assert(typeid(ab) == variant.type); //fails
variant=ac;
assert(typeid(ac) == variant.type); //fails
}
TypeInfo for highest type in hierarhy (class) when passed base type
How to handle this situation:
module typeTest;
class A{
void a(){}
}
class B:A{
int b(){
return 1;
}
}
class C:B,D{
string c(){
return "";
}
override int d() {
return 0;
}
}
interface D{
int d();
}
TypeInfo __typeInfo(T)(T t){
return typeid(T);
}
unittest{
A a= new A;
A b= new B;
A c = new C;
TypeInfo aInfo=__typeInfo(a);
TypeInfo bInfo=__typeInfo(b);
TypeInfo cInfo=__typeInfo(c);
assert(aInfo!=bInfo); //fails
assert(aInfo!=cInfo);//fails
assert(bInfo!=cInfo);//fails
}
Re: Using tango or other static lib in static lib
On Sunday, 13 March 2016 at 01:08:29 UTC, Mike Parker wrote: On Sunday, 13 March 2016 at 01:06:33 UTC, Mike Parker wrote: it. Assuming both files live in the same directory, they can be compiled with this command: Somehow I deleted that line: dmd main.d something.d Wow. Thank You very much for so wide description! I will try it and see if have any more questions. Cheers
Using tango or other static lib in static lib
At beginning I want to say that I'm Java devloper so most of
linking, joining, dependent classes, libs could be solve with
simple 3 click in eclipse so please be patient with me :).
I'm using Mono-D under Ubuntu 14.04 to create my project it would
be a library for further development process, but I'm a guy who
don't want to invite wheel again and again, so i wanted to use
Tango-D2 (for now HashMap implemenetation). From what i red you
cant import one static library with another but somehow import o.
files, or just copy sources .d to proper folder and use them as
yours (with proper license of course). Tango-D2 by itself
compiles nicely with bob and produces many .o files. How to use
them though ?
If using sources by just copping them into one folder, creating
Mono-D project, dmd complains about many, many errors, mostly
import errors (in tango.sys.win32). I fixed them adding version
to each of included files and adding some imports first:
module tango.sys.win32
version(Windows){
...
...
}
But i think I'm doing something wrong, if Tango-D2 compiles with
bob it should also by creating project in Mono-D (or this is
linking problem ?). In Mono-D there is also possibility in
Project-> Options-> Build-> Compiling to add Libraries (there is
a tick Link static libraries from nested dependencies) how to use
this ? Or rather how should i obtain what i want ?
Re: Accessing all data in TypeTupple (AliasSeq) and stringify them
On Thursday, 25 February 2016 at 14:29:30 UTC, Nicholas Wilson
wrote:
On Thursday, 25 February 2016 at 13:16:43 UTC, Voitech wrote:
Hi, I have some code processing functions definition in
compile time, I want to override
them in some other class but not explicitly so created this
code:
template MixinFunction(alias attributes,alias returnType,alias
name,alias parameters,alias bodyy){
enum string MixinFunction = format(q{
%s %s %s(%s){
%s
}
},attributes,returnType,name,parameters,bodyy);
}
unittest{
alias func=MixinFunction!("static","void","testFunc","int
a,int b",q{
import std.stdio;
writeln("im void body");
});
pragma(msg,func);
mixin(func);
}
Now i acquired all data like return type, parameters but need
to turn them into string for example function parameters must
have form of:
for function func:
void func(int a,string b){}
alias parameters=Parameters!func;
returns me AliasSeq!(int,string)
I want to to turn them into string: like "int param0, string
param1", but in template
template AliasSeqToString(TList...){
enum AliasSeqToString= ... //each ?
}
How to operate on TypeTuple/AliasSeq elemens withouth foreach ?
You can (see std.meta/(std.traits?) , with recursive
templates), but there is nothing stopping from using
for/foreach in a template
this should do what you want
string[] functionSig;
string[] params;
foreach(s; Parameters!T)) // returns AliasSeq of types
{
params ~=s.stringof;
}
string[] pits;
foreach(p; ParameterIdentifierTuple!(T)); // returns AliasSeq
of strings
{
pits ~=p;
}
and the either join(er) or do as you see fit.
or use plain old for
for(auto i=0;i< pits.length; i++)
{
functionSig ~= params[i];
functionSig ~= pits[i];
}
writeln(functionSig);
// should print ["int" , "param0" , "string" , "param1"]
Nic
Thank You for answering, well i wanted to make all of this in
template block, not using template functions (testing if it is
possible), but i'm getting error when i try to create something
like
template TupleToString(TList...){
string a;
foreach(T;TList){ // Error: declaration expected, not
'foreach'
a~=T.stringof;
}
enum string TupleToString=a;
}
Of course i can use template function, but wanted to know if can
omit this.
Cheers Voitech
Accessing all data in TypeTupple (AliasSeq) and stringify them
Hi, I have some code processing functions definition in compile
time, I want to override
them in some other class but not explicitly so created this code:
template MixinFunction(alias attributes,alias returnType,alias
name,alias parameters,alias bodyy){
enum string MixinFunction = format(q{
%s %s %s(%s){
%s
}
},attributes,returnType,name,parameters,bodyy);
}
unittest{
alias func=MixinFunction!("static","void","testFunc","int a,int
b",q{
import std.stdio;
writeln("im void body");
});
pragma(msg,func);
mixin(func);
}
Now i acquired all data like return type, parameters but need to
turn them into string for example function parameters must have
form of:
for function func:
void func(int a,string b){}
alias parameters=Parameters!func;
returns me AliasSeq!(int,string)
I want to to turn them into string: like "int param0, string
param1", but in template
template AliasSeqToString(TList...){
enum AliasSeqToString= ... //each ?
}
How to operate on TypeTuple/AliasSeq elemens withouth foreach ?
Create a proxy
Hi, I'm trying to create a proxy with automatic method generation
. Let say i hava Service object which can be Local service and
Remote service. f.e:
interface Service{
string serviceInfo();
}
interface LocalService:Service{
int doSmth(string param);
}
class LocalServiceImpl:LocalService{
override string serviceInfo(){
return "i am local";
}
override int doSmth(string param){
return param.lenght;
}
}
And now i want to create a proxy, which for client is visible as
LocalService
class RemoteServiceProxy:LocalService{
Serializer serializer;
HttpClient client;
Deserializer deserializer
this(Serializer serializer,Deserializer deserializer,HttpClient
client){
this.serializer=serializer;
this.client=client;
this.deserializer=deserializer;
}
override string serviceInfo(){
return "i am remote";
}
override int doSmth(string param){
string json= serializer.toJson!(doSmth,int,param)();
string response=client.send(json);
return deserializer.fromJson!(response,int)();
}
}
So RemoteServiceProxy should serialize method name, return type
and parameters and send it to some server. On server this should
be executed (for now i don't care about errors) and returned as
proper value.
The problem is i don't want to override every remote service
method i will create in interface (LocalService) i want them to
be generated depending on return, and parameter types. It will
always the same schema: serialize ... http request ...
deserialize ... return value (throw Excepion).
How to handle this corectly ? I was trying to use mixins for this
i created some functions but this not working don't know why
string createFunction(R, alias name)(){
static if(is(R==void)){
return mixin(createVoidFunction(name)());
}
static if(!is(R==void)){
return mixin(createNonVoidFunction!(R,name)());
}
}
string createVoidFunction(alias name)(){
return format(q{
void %s(){
writeln(" im void function");
}
},name);
}
string createNonVoidFunction(R,alias name)(){
return format(q{
%s %s(){
writeln("im non void function");
return %s;
}
}, R.stringof,name,R.init);
}
unittest{
mixin(createFunction!(int,"nonVoid")());
}
There is also a Proxy template in std.typecons but i don't
understand how it works or even can it be used in this case. How
to handle this ?
Re: Algebraic template instance holder
On Wednesday, 10 February 2016 at 20:53:15 UTC, ZombineDev wrote:
On Wednesday, 10 February 2016 at 10:31:34 UTC, Voitech wrote:
Hi, why this is not working ?
class Base{
int a;
}
class BaseTemplate(E):Base{
E value;
this(E value){
this.value=value;
}
}
class Concrete:BaseTemplate!int{
this(int value){
super(value);
}
}
unittest{
Algebraic!(Concrete) holder;
Concrete a=new Concrete(4);
holder =Algebraic!Concrete(a);
}
This is a bug. I filled it as:
https://issues.dlang.org/show_bug.cgi?id=15670
I will see if I can fix it tomorrow.
Hi @ZombineDev have you by chance looked at this bug ?
Algebraic template instance holder
Hi, why this is not working ?
class Base{
int a;
}
class BaseTemplate(E):Base{
E value;
this(E value){
this.value=value;
}
}
class Concrete:BaseTemplate!int{
this(int value){
super(value);
}
}
unittest{
Algebraic!(Concrete) holder;
Concrete a=new Concrete(4);
holder =Algebraic!Concrete(a);
}
Re: Dynamic Ctors ?
On Monday, 8 February 2016 at 15:09:30 UTC, Kagamin wrote: http://dpaste.dzfl.pl/1f25ac34c1ee You need Tuple, not Algebraic. Algebraic stores only one value of one type from a set, like Variant. Thank you for answering. You right if i would want to store all types of T.. in an Inner instance. But my conception was bad from the beginning. I want to store only one type of value in Inner instance. I just wanted to create generic constructor for each of Type which is invalid, cause instance holds value of single type that's why it is not parametrized by itself.
Re: Dynamic Ctors ?
On Monday, 8 February 2016 at 07:08:58 UTC, Voitech wrote:
On Saturday, 6 February 2016 at 23:35:17 UTC, Ali Çehreli wrote:
On 02/06/2016 10:05 AM, Voitech wrote:
> [...]
You can use string mixins (makeCtor and makeCtors):
string makeCtor(T)() {
import std.string : format;
[...]
Thank you very much for answering.
Cheers
Unfortunately this doesn't work as I'am trying to assign value
from ctor to member something like:
this(%s value){
this.value=value;
}
it gives me
Error: memcpy cannot be interpreted at compile time, because it
has no available source code.
Probably this is caused by declaration of member which is also
parametrized with T...
Member is:
Algebraic!(T) value;
So declaration of this mixin constructors are done before
variable value is declared (compilation)?
Is there any field in class that would contain ctors ? Something
like __ctors ?
i could try to init this(T... value) constructors in static
constructor using delegates/functions. Something like:
template Outer(T...){
class Inner{
Algebraic!(T) value;
alias ctor(Type) =Inner delegate (Type value);
static this(){
foreach(Type;T){
ctor!(Type) c={
this.value=value;
};
__ctors~=c; // ?
}
}
}
Re: Dynamic Ctors ?
On Saturday, 6 February 2016 at 23:35:17 UTC, Ali Çehreli wrote:
On 02/06/2016 10:05 AM, Voitech wrote:
> [...]
You can use string mixins (makeCtor and makeCtors):
string makeCtor(T)() {
import std.string : format;
[...]
Thank you very much for answering.
Cheers
Re: Dynamic Ctors ?
On Saturday, 6 February 2016 at 18:05:05 UTC, Voitech wrote:
Hi, i have a variadic args template, with a class inside
something like:
template foo(T...){
class Inner(){
...
...
}
}
Now i want to make Inner create or i will create manually,
constructor for each of T... parameter types, but don't know
what is syntax for it. I found that there is possibility to
initialize T... types static variables with AliasSeq!(T) but
how to do this automatically, or with static ifs,for
constructors ?
I tried ...
template foo(T...){
alias Types=AliasSeq!(T);
Algebraic!(T) value;
this(Types value)
this.value=value;
}
}
But this dosn't work
This gives Error: memcpy cannot be interpreted at compile time,
because it has no available source code
Dynamic Ctors ?
Hi, i have a variadic args template, with a class inside
something like:
template foo(T...){
class Inner(){
...
...
}
}
Now i want to make Inner create or i will create manually,
constructor for each of T... parameter types, but don't know what
is syntax for it. I found that there is possibility to initialize
T... types static variables with AliasSeq!(T) but how to do this
automatically, or with static ifs,for constructors ?
I tried ...
template foo(T...){
alias Types=AliasSeq!(T);
Algebraic!(T) value;
this(Types value)
this.value=value;
}
}
But this dosn't work
Re: Variadic template parameters T... bounding
On Tuesday, 2 February 2016 at 13:52:55 UTC, Marc Schütz wrote: On Tuesday, 2 February 2016 at 13:20:33 UTC, Voitech wrote: [...] Two possible solutions... If you don't need to know the number of arguments at compile time, you can use normal variadic arguments: [...] Thank you I'll try that.
Variadic template parameters T... bounding
Hi, Is it possible to bound T... in template with some type ? For single Parameter declaration it can be done by T:SomeType but variadics does not seems to have that possibility ? Cheers
Types as keys
Hello, I'm having problem with converting from Java style coding
to D, probably doing wrong something. I want to have a map
(associative array) which will return specific object depending
on provided key. Key is a type of other object. Let say i want to
hold single instances of some kind of parser for each key object
types.
class BaseFooBar{}
class Foo:BaseFooBar{
...
}
class Bar:BaseFooBar{
}
BaseParser{}
Parser(T) :BaseParser{
abstract string parse(T value);
}
ParserOne:Parser!Foo{
override string parse(Foo value){
...
}
ParserTwo:Parser!Bar{
override string parse(Bar value){
...
}
Parser[TypeInfo] container;
container~=new ParserOne();
container~=new ParserTwo();
Now i have some data Foo and some Bar in array and each one must
be parsed using proper parser
parserFoobars(BaseFooBar[] values){
foreach(BaseFooBar foobar;values){
BaseParser parser=container[typeid(foobar)];
...
Now i would have to cast check if parser is ParserOne or
ParserTwo and then cast foobar to Bar or Foo depending on which
parser has been retrieved. This has no sense ... In Java i could
place generic code in BaseParser and depending on FooBar type i
will get proper parser from map, and values would be parsed
without casting.
How to handle this correctly?
Re: Templates, templates, templates...
On Saturday, 23 January 2016 at 13:19:34 UTC, anonymous wrote:
On 23.01.2016 12:30, Voitech wrote:
Ok so i want to hold different types in LogicRule maybe
Algebraic
implementation would do?
private alias ControllTemplate(T) =Rule!(T,ControllFlag);
private alias SymbolRule =ControllTemplate!(SymbolType);
private alias StringRule =ControllTemplate!(SymbolRule[]);
private alias LogicTemplate(T...)
=Rule!(Algebraic!(ControllTemplate(T))[],LogicFlag); <--error
You're missing an exclamation mark there, and you've got the
order of Algebraic and ControllTemplate wrong. This compiles:
private alias LogicTemplate(T...) =
Rule!(ControllTemplate!(Algebraic!T)[],LogicFlag);
private alias AlgebraicLogicRule =
LogicTemplate!(SymbolRule,StringRule);
error:
Error: cannot pass type (Rule!(SymbolType, ControllFlag),
Rule!(Rule!(SymbolType, ControllFlag)[], ControllFlag)) as a
function
argument
[...]
Is there any nicer way to handle this case ?
Instead of Algebraic you could use a common base class, or
interface, for the Rule instantiations:
abstract class RuleBase
{
... whatever common functionality rules have ...
}
class Rule(V,F) : RuleBase { ...}
But I have to say that I'm having trouble making sense of all
that class and template complexity, and how it helps in
actually validating user input.
Since this is a parsing thing, you may want to look into
writing parsers an/or using a parse generator. I think Pegged
is the most popular one for D.
http://code.dlang.org/packages/pegged
Hi, thanks for answering. The complexity is unnecessary as you
said. I'm just experimenting with D language. I think i try to
finish implementation in my own way and then will look how it may
be done with http://code.dlang.org/packages/pegged to have a full
spectrum of possibilities.
I added base class for Rule -> BaseRule. But this class is just a
shell without implementation.
Is there any way to avoid this ?
Templates, templates, templates...
Hi, I have a problem with creating proper inheritance chain with
templates. First i will give some background about my problem.
I'm trying to create a validator for math calculation
expressions. I don't want to use regexps as this is approach
gives me headache and probably will not allow further extension i
want. For now expressions should look like this:
1+2+3/4, -(5*(25-5)/19), sqrt(-5/-6*(212)) etc.
So each of charactes is parsed to something like PrimaryElement
class PrimaryElement {
const dchar value;
SymbolType symbolType;
}
SymbolsType is an enum which contains:
EXPR_START,+,-,/,DIGIT,(,),.,EXPR_END
So now i want to create validator for input so user couldn't
insert something like:
/00..34-+/493 but only 0.34-493. I want to divide it into phases.
First phase is SymbolType validation so it will handles problems
like:
+-/345..3 but not .234+3-53
Second phase will take care about value validation so user cant
insert .0+3 but only 0.000+3
Third phase would be executed to check expression is completed
and not allow to calculate expression for situations like
0.000+3, 3-3+4.5+ or 364/4-5.3+(
Now i'm trying to implement phase one. So i create
PrimaryElementProcessor which will take some kind of rules and
check PrimaryElement[] that way if divided parts of array fits
into one of rules then it is valid. Rules will be trimmed to size
of expression if necessary.
Model and constants declaration looks like this:
private enum ControllFlag{
none,ommitable,repeatable
}
private enum LogicFlag{
none,or,and
}
private class Rule(V,F){
V value;
F flag;
this(){
}
this(V value){
this.value=value;
}
this(V value,F flag){
this.value=value;
this.flag=flag;
}
}
private alias ControllTemplate(T) =Rule!(T,ControllFlag);
private alias SymbolRule =ControllTemplate!(SymbolType);
private alias StringRule =ControllTemplate!(SymbolRule[]);
private alias LogicTemplate(T...)
=Rule!(ControllTemplate(T)[],LogicFlag);
private alias LogicRule=LogicTemplate!([SymbolRule,StringRule]);
<--error
So i first want to handle case like D. or DD where D
is Digit
instantiation code:
SymbolRule digitRule = new
SymbolRule(SymbolType.digit,ControllFlag.repeatable);
SymbolRule commaRule = new SymbolRule(SymbolType.comma);
StringRule numericRule = new
StringRule([digitRule,commaRule,digitRule]);
LogicRule decimalRule = new
LogicRule([digitRule,numericRule],LogicFlag.or);
error:
Error: type Rule!(Rule!(SymbolType, ControllFlag)[],
ControllFlag) has no value
Ok so i want to hold different types in LogicRule maybe Algebraic
implementation would do?
private alias ControllTemplate(T) =Rule!(T,ControllFlag);
private alias SymbolRule =ControllTemplate!(SymbolType);
private alias StringRule =ControllTemplate!(SymbolRule[]);
private alias LogicTemplate(T...)
=Rule!(Algebraic!(ControllTemplate(T))[],LogicFlag); <--error
private alias AlgebraicLogicRule =
LogicTemplate!(SymbolRule,StringRule);
error:
Error: cannot pass type (Rule!(SymbolType, ControllFlag),
Rule!(Rule!(SymbolType, ControllFlag)[], ControllFlag)) as a
function argument
So maybe something simpler:
private alias ControllTemplate(T) =Rule!(T,ControllFlag);
private alias SymbolRule =ControllTemplate!(SymbolType);
private alias StringRule =ControllTemplate!(SymbolRule[]);
private alias SimpleLogicRule
=Rule!(Algebraic!(SymbolRule,StringRule)[],LogicFlag);
Compiles but... when i try to instantiate SimpleLogicRule like
SymbolRule digitRule = new
SymbolRule(SymbolType.digit,ControllFlag.repeatable);
SymbolRule commaRule = new SymbolRule(SymbolType.comma);
StringRule numericRule = new
StringRule([digitRule,commaRule,digitRule]);
SimpleLogicRule decimalRule = new
SimpleLogicRule([digitRule,numericRule],LogicFlag.or); <--- error
i get error:
None of the overloads of '__ctor' are callable using argument
types (Object[], LogicFlag), candidates are: ...
So i understand compiler can't cast/extract array of different
types to known type.
I created a wrapper for this two types SymbolRule and StringRule
and init it somewhere before passing to LogicRule ctor. This
approach makes a lot of boilerplate code for example:
alias Wrapper = Algebraic!(SymbolRule,StringRule);
alias LogicRule =Rule!(Wrapper[],LogicFlag);
SymbolRule digitRule = new
SymbolRule(SymbolType.digit,ControllFlag.repeatable);
SymbolRule commaRule = new SymbolRule(SymbolType.comma);
StringRule numericRule = new
StringRule([digitRule,commaRule,digitRule]);
Wrapper digitRuleWrapper =digitRule; <-- how to ommit this ?
Wrapper numericRuleWrapper =numericRule; <-- how to ommit this ?
LogicRule decimalRule=new
LogicRule([digitRuleWrapper,numericRuleWrapper],LogicFlag.or);
Is there any nicer way to handle this case ?
Cheers Voitech.
Java wildcards... in D
Hi. I'm trying to parse an simple string expression to something
like Element array. Each Element can have a value of unknown
type, which will be further combined and calculated to let say
real/double/float value, no mather.
In Java i had something like generics and this could be
implemented like:
class Element {
T value;
Element(T value){
this.value=value;
}
}
class Parser{
Collection parse(String expression){
Collection retVal = new ArrayList<>();
//"expression" would be parser but for this example lets say
we just create new elements
Element e1= new Element<>();
e1.value=3;
Element e2 = new Element<>();
e2.value="+"
retValue.add(e1);
retValue.add(e2);
...
return retValue;
}
}
And then in other class not connected through module or template
parameter or anything i could call it just:
Parser p = new Parser();
Collection elements=p.parse("(1+2+3)/6");
and then check weather (element.value instanceof Operator) or
other stuff.
if i do something like this in D:
module calculator;
class Element(T) {
T value;
this(T value){
this.value=value;
}
}
and then:
Element[] parse(string expression){
Element[] returnSlice;
...
//"expression" would be parser but for this example
lets say we just create new elements
Element!(int) e1 = new Element();
e1.value=3;
Element!(string) e2= new Element();
e2.value="+";
returnSlice~=e1;
returnSlice~=e2;
return returnSlice;
}
I'm getting error:
class calculator.Element used as a type.
How to represent this class template parameter T of Element(T) as
wildcard Element(?) ??
Cheers Voitech
Re: Java wildcards... in D
On Monday, 18 January 2016 at 21:15:51 UTC, Chris Wright wrote:
On Mon, 18 Jan 2016 19:19:22 +, Voitech wrote:
Hi. I'm trying to parse an simple string expression to
something like Element array. Each Element can have a value of
unknown type, which will be further combined and calculated to
let say real/double/float value, no mather.
In Java, Element is always Element behind the
scenes, and there's only one type.
In D, Element(T) is a template that produces a type.
Element!int and Element!Object are entirely different and,
thanks to what templates allow you to do, the compiler can't
assume any relationship between the two.
You have to establish that relationship manually by creating a
base type:
abstract class BaseElement {
}
class Element(T) : BaseElement {
T value;
}
Alternatively, if this is not appropriate to your usecase, you
may want to look at std.variant, which explicitly implements
value boxing.
Thank you for answering. I think i will use std.variant.Algebraic
implementation for my needs. But about Algebraic... why first
template parameter of it must be always int. Let say i want to
store only real and string in Algebraic no int.
if i try to do something like :
alias Element =Algebraic!(real,string);
i will get:
Cannot store a int in a VariantN!(16LU, real, string)
if i declare as:
alias Element =Algebraic!(int,real,string);
this will be ok.
But anything other than Algebraic!(int,x,y,z...) doesn't compile,
like:
alias Element =Algebraic!(uint,bool,string); //compilation error
alias Element =Algebraic!(ulong,Object,bool); //compilation error
alias Element =Algebraic!(long,real,string); //compilation error
Why is that ?
Cheers Voitech.
Struct Union behavior
Hello, i am new to D language and trying to learn it by coding.
I compile my programs on Xubuntu 14.04 with DMD64 D Compiler
v2.069.2.
So i have a struct/union which contains two fields representing
real and string values:
public union Element
{
private real _value;
private string _rawValue;
@property{
real value(){
return _value;
}
void value(real value){
_value=value;
}
}
@property {
ref string rawValue(){
return _rawValue;
}
void rawValue(ref string value){
_rawValue=value;
}
}
public Element opBinary(string op)(Element other){
Element newElement;
real value=mixin("this.value "~op~"other.value");
newElement.value=value;
return newElement;
}
public bool opEquals(Element other){
if(this.rawValue == null && other.rawValue == null){
return this.opEquals(other.rawValue);
}
return this.opEquals(other.value);
}
public bool opEquals(real value){
return this.value==value;
}
public bool opEquals(string rawValue){
return this.rawValue==rawValue;
}
unittest{
Element e1 = {4},e2 ={5};
writeln("e1 is at address: ",);
writeln("e2 is at address: ",);
writeln("e1.value is at address: ",_value);
writeln("e2.value is at address: ",_value);
assert(e1+e2==9);
}
unittest{
Element s1={_rawValue:"+"},s2,s3,s4;
writeln("s1 is at address: ",);
writeln("s2 is at address: ",);
writeln("s3 is at address: ",);
writeln("s1.value is at address: ",_value);
writeln("s2.value is at address: ",_value);
writeln("s3.value is at address: ",_value);
writeln("s4.value is at address: ",_value);
writeln("s1.rawValue ",s1._rawValue);
writeln("s1.value: ",s1._value);
writeln("s2.value: ",s2._value);
writeln("s3.value: ",s3._value);
writeln("s4.value: ",s4._value );
assert(s1!=s2);
}
}
The unit test results are:
e1 is at address: 7FFCEFBA7510
e2 is at address: 7FFCEFBA7520
e1.value is at address: 7FFCEFBA7510
e2.value is at address: 7FFCEFBA7520
s1 is at address: 7FFCEFBA7500
s2 is at address: 7FFCEFBA7510
s3 is at address: 7FFCEFBA7520
s1.value is at address: 7FFCEFBA7500
s2.value is at address: 7FFCEFBA7510
s3.value is at address: 7FFCEFBA7520
s4.value is at address: 7FFCEFBA7530
s1.rawValue +
s1.value: 0.125
s2.value: 4
s3.value: 5
s4.value: 9
Can anyone tell me why s2,s3,s4 have initialized _value field?
Shouldn't it be collected by GC when first unit test (with e1,e2)
finishes ? If not how to handle this behavior, to use union
without preinitialized fields.
Re: Struct Union behavior
On Wednesday, 6 January 2016 at 12:25:31 UTC, Nicholas Wilson wrote: Probably because you are accessing uninitialised memory. the values 4,5,9 appear in the first unittest and are left on the stack. Unions ,unlike structs, do not initialise their fields because it does not make sense to do so because the memory aliases. This can be observed by looking at the size of element (16 bytes) which is less than the size of an array (on 64 bit systems) , 2*8 bytes plus size of a real (8 or 10 bytes (x86/64)). [...] Thank you for your answer it was very helpful :) Cheers.
