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Home » U++ Library support » U++ Core » NEW: generic Toupel grouper
Re: NEW: generic Toupel grouper [message #28129 is a reply to message #28128] Tue, 17 August 2010 22:52 Go to previous messageGo to next message
dolik.rce is currently offline  dolik.rce
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kohait00 wrote on Tue, 17 August 2010 22:22

Quote:

Don't forget about the GetCount()
i dont think that it is that much of use either. becasue everything is know at compiletime, and Tupel is not meant to be a base class. so i cant imagine any practicle usecase. i'd prefer to, as mirek statet, have it as simple as possible, and serve its due as beeing a compile time known simple strong type container / grouper of data types. not more nor less, except there is more things to have on it, that are of real use.

The main reason I want GetCount() is that it is in every container, from Vector to String. You are right that everything is known at compile time, but it doesn't really mean that you know everything when you write some code Smile E.g.: Sometimes there are situations where you create templated function which iterates through a container. It doesn't even have to be you who uses the code in the end.

One of the reasons why I like U++ so much is its consistency of interfaces. I feel safe to write template or macro that is doing something general with only basic assumptions about interface, often without knowing what some crazy user of my code will send to it Smile And it is not only about iterating in containers - also ToString (DUMP and LOG are great example of what I tried to describe in previous paragraph), Serialize, Null constructors, operator<<= etc.

Honza

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Re: NEW: generic Toupel grouper [message #28131 is a reply to message #28129] Tue, 17 August 2010 23:21 Go to previous messageGo to next message
kohait00 is currently offline  kohait00
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well it's hard to think of Tupel beeing a 'iterable' container.
but i can 'feel' the need somehow as well, especially looking at Value operator[]. so here the type is actually hidden. here is another possib for GetCount()


	int GetCount() const
	{
		int c = 2;
		if(typeid(T3) != typeid(Nuller)) ++c;
		if(typeid(T4) != typeid(Nuller)) ++c;
		if(typeid(T5) != typeid(Nuller)) ++c;
		return c;
	}

but doesnt save us from things like
Typel<int, int, Nuller, float> t; //float type unreachable
for(int i = 0; i<t.GetCount(); i++)
   Value v = t[i];

but here, the user is dumb Smile

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Re: NEW: generic Toupel grouper [message #28133 is a reply to message #28131] Tue, 17 August 2010 23:53 Go to previous messageGo to next message
dolik.rce is currently offline  dolik.rce
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I would use
int GetCount() const
	{
		if(typeid(T5) != typeid(Nuller)) return 5;
		if(typeid(T4) != typeid(Nuller)) return 4;
		if(typeid(T3) != typeid(Nuller)) return 3;
		return 2;
	}

That works even for the dumb user Wink
Honza

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Re: NEW: generic Toupel grouper [message #28152 is a reply to message #28133] Thu, 19 August 2010 08:30 Go to previous messageGo to next message
kohait00 is currently offline  kohait00
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thats way better. one would need to check for intermediate Nuller though anyway, beeing that the case, why not simply do this Smile
inline int GetCount() const { return 5; }


so it's up to mirek to decide what happens with this stuff

[Updated on: Thu, 19 August 2010 08:30]

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Re: NEW: generic Toupel grouper [message #28365 is a reply to message #28152] Mon, 30 August 2010 20:57 Go to previous messageGo to next message
mirek is currently offline  mirek
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kohait00 wrote on Thu, 19 August 2010 02:30

thats way better. one would need to check for intermediate Nuller though anyway, beeing that the case, why not simply do this Smile
inline int GetCount() const { return 5; }


so it's up to mirek to decide what happens with this stuff



I believe it is not very helpful to mix Tuples with Value or try to pretend they are maps. In fact, ValueArray covers such usage pretty well IMO.

I believe that the common usage scenario is in cases where you need "quick" struct which is not worth defining, like

static Tuple<int, const char *> mapping[] = {
   0, "foo",
   1, "bar"
}


In fact, the only think to resolve is how to name its members.

Right now, "a, b, c, d, e..." sound like the best option. STL templated indexing seems overengineered to me, "first, second, third..." are too long and "v0, v1, v2, v3..." have "zero index issue".

Well, maybe something like "key, value, value1, value2" would reflect the most typical use.

More ideas? Or letters are it?

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Re: NEW: generic Toupel grouper [message #28366 is a reply to message #28365] Mon, 30 August 2010 22:23 Go to previous messageGo to next message
kohait00 is currently offline  kohait00
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i'd prefer a,b,c,d,e...
its just sweeter Smile and one can give it the meaning it needs, key, value...is too specific already

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Re: NEW: generic Toupel grouper [message #28367 is a reply to message #27972] Mon, 30 August 2010 23:13 Go to previous messageGo to next message
dolik.rce is currently offline  dolik.rce
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I agree with the a,b,c,d,e... too. It is nice and simple and fast to write. One more question is how many values should be supported. I personally think that a-f should be about enough...

Honza

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Re: NEW: generic Toupel grouper [message #28369 is a reply to message #28367] Tue, 31 August 2010 08:31 Go to previous messageGo to next message
kohait00 is currently offline  kohait00
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if more is needed, this should be possible.. Smile
Tupel<int,float,int,float,Tupel<String,char,String,char,double> >


in terms of Tupel as container: Tupel is actually no container..here mirek is right.its a grouper class. anyway, in case such a behaviour is needed, it can be subsequently added deriving.

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Re: NEW: generic Toupel grouper [message #28370 is a reply to message #28369] Tue, 31 August 2010 08:44 Go to previous messageGo to next message
kohait00 is currently offline  kohait00
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so here is a cleaned up proposal..
template<class T1, class T2, class T3=EmptyClass, class T4=EmptyClass, class T5=EmptyClass>
class Tupel {
public:
	Tupel(const T1 & a, const T2 & b, const T3 & c, const T4 & d, const T5 & e) 
		: a(a), b(b), c(c), d(d), e(e) {}
	Tupel() {}
	T1 a; T2 b; T3 c; T4 d; T5 e;
};

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Re: NEW: generic Toupel grouper [message #28371 is a reply to message #28370] Tue, 31 August 2010 09:20 Go to previous messageGo to next message
cbpporter is currently offline  cbpporter
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Just a little nitpicking: it is called tuple, unless I am not aware of some British/American alternate spelling.

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Re: NEW: generic Toupel grouper [message #28372 is a reply to message #28371] Tue, 31 August 2010 09:44 Go to previous messageGo to next message
kohait00 is currently offline  kohait00
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typedef Tupel Tuple; Very Happy
no, you're absolutely right.

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Re: NEW: generic Toupel grouper [message #28378 is a reply to message #28367] Tue, 31 August 2010 13:29 Go to previous messageGo to next message
mirek is currently offline  mirek
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dolik.rce wrote on Mon, 30 August 2010 17:13

I agree with the a,b,c,d,e... too. It is nice and simple and fast to write. One more question is how many values should be supported. I personally think that a-f should be about enough...

Honza


IMO, 4 is more than enough....

Here is what I got after bit of experimenting:

template <typename A, typename B>
struct Tuple2 {
	union {
		A a;
		A key;
	};
	union {
		B b;
		B value;
	};
	
	int  Compare(const Tuple2& x) const       { return CombineCompare(a, x.a)(b, x.b); }
	bool operator==(const Tuple2& x) const    { return Compare(x) == 0; }
	bool operator!=(const Tuple2& x) const    { return Compare(x) != 0; }
	bool operator<=(const Tuple2& x) const    { return Compare(x) <= 0; }
	bool operator>=(const Tuple2& x) const    { return Compare(x) >= 0; }
	bool operator<(const Tuple2& x) const     { return Compare(x) != 0; }
	bool operator>(const Tuple2& x) const     { return Compare(x) != 0; }
	
	unsigned GetHashValue() const             { return CombineHash(a, b); }
};

template <typename A, typename B>
inline Tuple2<A, B> MakeTuple(const A& a, const B& b)
{
	Tuple2<A, B> r;
	r.a = a;
	r.b = b;
	return r;
}

template <typename A, typename B, typename C>
struct Tuple3 {
	union {
		A a;
		A key;
	};
	union {
		B b;
		B value;
	};
	union {
		C c;
		C value1;
	};
	
	int  Compare(const Tuple3& x) const       { return CombineCompare(a, x.a)(b, x.b)(c, x.c); }
	bool operator==(const Tuple3& x) const    { return Compare(x) == 0; }
	bool operator!=(const Tuple3& x) const    { return Compare(x) != 0; }
	bool operator<=(const Tuple3& x) const    { return Compare(x) <= 0; }
	bool operator>=(const Tuple3& x) const    { return Compare(x) >= 0; }
	bool operator<(const Tuple3& x) const     { return Compare(x) != 0; }
	bool operator>(const Tuple3& x) const     { return Compare(x) != 0; }
	
	unsigned GetHashValue() const             { return CombineHash(a, b, c); }
};

template <typename A, typename B, typename C>
inline Tuple3<A, B, C> MakeTuple(const A& a, const B& b, const C& c)
{
	Tuple3<A, B, C> r;
	r.a = a;
	r.b = b;
	r.c = c;
	return r;
}

template <typename A, typename B, typename C, typename D>
struct Tuple4 {
	union {
		A a;
		A key;
	};
	union {
		B b;
		B value;
	};
	union {
		C c;
		C value1;
	};
	union {
		D d;
		D value2;
	};
	
	int  Compare(const Tuple4& x) const       { return CombineCompare(a, x.a)(b, x.b)(c, x.c)(d, x.d); }
	bool operator==(const Tuple4& x) const    { return Compare(x) == 0; }
	bool operator!=(const Tuple4& x) const    { return Compare(x) != 0; }
	bool operator<=(const Tuple4& x) const    { return Compare(x) <= 0; }
	bool operator>=(const Tuple4& x) const    { return Compare(x) >= 0; }
	bool operator<(const Tuple4& x) const     { return Compare(x) != 0; }
	bool operator>(const Tuple4& x) const     { return Compare(x) != 0; }
	
	unsigned GetHashValue() const             { return CombineHash(a, b, c, d); }
};

template <typename A, typename B, typename C, typename D>
inline Tuple4<A, B, C, D> MakeTuple(const A& a, const B& b, const C& c, const D& d)
{
	Tuple4<A, B, C, D> r;
	r.a = a;
	r.b = b;
	r.c = c;
	r.d = d;
	return r;
}

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Re: NEW: generic Toupel grouper [message #28379 is a reply to message #28378] Tue, 31 August 2010 13:34 Go to previous messageGo to next message
mirek is currently offline  mirek
Messages: 13975
Registered: November 2005
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Upgrade:

template <typename A, typename B>
struct Tuple2 {
	union {
		A a;
		A key;
	};
	union {
		B b;
		B value;
	};
	
	bool operator==(const Tuple2& x) const    { return a == x.a && b == x.b; }
	bool operator!=(const Tuple2& x) const    { return !operator==(x); }

	int  Compare(const Tuple2& x) const       { return CombineCompare(a, x.a)(b, x.b); }
	bool operator<=(const Tuple2& x) const    { return Compare(x) <= 0; }
	bool operator>=(const Tuple2& x) const    { return Compare(x) >= 0; }
	bool operator<(const Tuple2& x) const     { return Compare(x) != 0; }
	bool operator>(const Tuple2& x) const     { return Compare(x) != 0; }
	
	unsigned GetHashValue() const             { return CombineHash(a, b); }
};

template <typename A, typename B>
inline Tuple2<A, B> MakeTuple(const A& a, const B& b)
{
	Tuple2<A, B> r;
	r.a = a;
	r.b = b;
	return r;
}

template <typename A, typename B, typename C>
struct Tuple3 {
	union {
		A a;
		A key;
	};
	union {
		B b;
		B value;
	};
	union {
		C c;
		C value1;
	};
	
	bool operator==(const Tuple3& x) const    { return a == x.a && b == x.b && c == x.c; }
	bool operator!=(const Tuple3& x) const    { return !operator==(x); }

	int  Compare(const Tuple3& x) const       { return CombineCompare(a, x.a)(b, x.b)(c, x.c); }
	bool operator<=(const Tuple3& x) const    { return Compare(x) <= 0; }
	bool operator>=(const Tuple3& x) const    { return Compare(x) >= 0; }
	bool operator<(const Tuple3& x) const     { return Compare(x) != 0; }
	bool operator>(const Tuple3& x) const     { return Compare(x) != 0; }
	
	unsigned GetHashValue() const             { return CombineHash(a, b, c); }
};

template <typename A, typename B, typename C>
inline Tuple3<A, B, C> MakeTuple(const A& a, const B& b, const C& c)
{
	Tuple3<A, B, C> r;
	r.a = a;
	r.b = b;
	r.c = c;
	return r;
}

template <typename A, typename B, typename C, typename D>
struct Tuple4 {
	union {
		A a;
		A key;
	};
	union {
		B b;
		B value;
	};
	union {
		C c;
		C value1;
	};
	union {
		D d;
		D value2;
	};
	
	bool operator==(const Tuple4& x) const    { return a == x.a && b == x.b && c == x.c && d == x.d; }
	bool operator!=(const Tuple4& x) const    { return !operator==(x); }

	int  Compare(const Tuple4& x) const       { return CombineCompare(a, x.a)(b, x.b)(c, x.c)(d, x.d); }
	bool operator<=(const Tuple4& x) const    { return Compare(x) <= 0; }
	bool operator>=(const Tuple4& x) const    { return Compare(x) >= 0; }
	bool operator<(const Tuple4& x) const     { return Compare(x) != 0; }
	bool operator>(const Tuple4& x) const     { return Compare(x) != 0; }
	
	unsigned GetHashValue() const             { return CombineHash(a, b, c, d); }
};

template <typename A, typename B, typename C, typename D>
inline Tuple4<A, B, C, D> MakeTuple(const A& a, const B& b, const C& c, const D& d)
{
	Tuple4<A, B, C, D> r;
	r.a = a;
	r.b = b;
	r.c = c;
	r.d = d;
	return r;
}

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Re: NEW: generic Toupel grouper [message #28380 is a reply to message #28370] Tue, 31 August 2010 13:36 Go to previous messageGo to next message
mirek is currently offline  mirek
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kohait00 wrote on Tue, 31 August 2010 02:44

so here is a cleaned up proposal..
template<class T1, class T2, class T3=EmptyClass, class T4=EmptyClass, class T5=EmptyClass>
class Tupel {
public:
	Tupel(const T1 & a, const T2 & b, const T3 & c, const T4 & d, const T5 & e) 
		: a(a), b(b), c(c), d(d), e(e) {}
	Tupel() {}
	T1 a; T2 b; T3 c; T4 d; T5 e;
};



There are two troubles:

- sizeof(EmptyClass) == 1, and all these members make it impossible to be initialized with braced list.

- with constructor, again it cannot be initialized with braced list (which, for me, is very important)

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Re: NEW: generic Toupel grouper [message #28382 is a reply to message #28380] Tue, 31 August 2010 13:51 Go to previous messageGo to next message
kohait00 is currently offline  kohait00
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Registered: July 2009
Location: Germany
Experienced Contributor
nice work,

btw: doensnt ==, !=, etc imply a quite a lot on class capabilities

EmptyClass: what about a DummyClass
class DummyClass
{
public:
DummyClass() {}
DummyClass(const DummyClass&) {}
};

it even could derive from EmptyClass to compare maybe

[Updated on: Tue, 31 August 2010 13:55]

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Re: NEW: generic Toupel grouper [message #28386 is a reply to message #28382] Tue, 31 August 2010 14:04 Go to previous messageGo to next message
kohait00 is currently offline  kohait00
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void* is simple but makes things possible
template<class A, class B, class C=void*, class D=void*>
class Tupel {
public:
	Tupel(const A& a, const B& b, const C& c = NULL, const D& d = NULL) 
		: a(a), b(b), c(c), d(d) {}
	Tupel() {}
	A a; B b; C c; D d;
};


EDIT: union is problematic, if T=One<int> i.e.

template<class A, class B, class C=void*, class D=void*>
class Tupel {
public:
	Tupel(const A& a, const B& b, const C& c = NULL, const D& d = NULL) 
		: a(a), b(b), c(c), d(d) {}
	Tupel() {}
	union { A a, key, v1; };
	union { B b, value, v2; }; 
	union { C c, v3; };
	union { D d, v4; };
};


Quote:



error: member 'Upp::One<int> Tupel<int, Upp::One<int>, Upp::String, int>::<anonymous union>::b' with constructor not allowe
d in union


TDMGCC

[Updated on: Tue, 31 August 2010 14:09]

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Re: NEW: generic Toupel grouper [message #28389 is a reply to message #28386] Tue, 31 August 2010 14:18 Go to previous messageGo to next message
kohait00 is currently offline  kohait00
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i'd suggest to leave it simple..just as u said.

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Re: NEW: generic Toupel grouper [message #28393 is a reply to message #28382] Tue, 31 August 2010 15:21 Go to previous messageGo to next message
mirek is currently offline  mirek
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kohait00 wrote on Tue, 31 August 2010 07:51

nice work,

btw: doensnt ==, !=, etc imply a quite a lot on class capabilities



It does, but it is not a problem, because compiler will not instatiate methods unless requested by using them. (Unless I am terribly mistaken Smile.

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Re: NEW: generic Toupel grouper [message #28394 is a reply to message #28386] Tue, 31 August 2010 15:23 Go to previous messageGo to next message
mirek is currently offline  mirek
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kohait00 wrote on Tue, 31 August 2010 08:04


EDIT: union is problematic, if T=One<int> i.e.



Ops, good point. What a pity, I guess I will have to live without 'key' Smile

Mirek

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Re: NEW: generic Toupel grouper [message #28395 is a reply to message #28393] Tue, 31 August 2010 15:31 Go to previous messageGo to previous message
kohait00 is currently offline  kohait00
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MSC i.e. is not even complaining about mistyped template implementations, as long as they are not instantiated. GCC is better here, it checks implementation. but of corse code instantiation is another topic..

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