Generics - can i use the same generic name for all situations?

[Dmitry Nogin]

Hi,

I would like to use dictionaries to implement my property value storing mechanics.
(I have a lot but many of them are just about to keep <nullmost of the time, so it might save a lot of memory.)

So, my solution is:

class Person

{

private readonly ReferenceStock< string_strings = new ReferenceStock< string>();

private readonly ValueStock<int_ ints = new ValueStock<int> ();

private readonly ValueStock<bool _bools = new ValueStock<bool >();



public string Name

{

get { return _strings["Name"]; }

set { _strings["Name"] = value; }

}



public int? Age

{

get { return _ints["Age"]; }

set { _ints["Age"] = value; }

}


public int Rating

{

get { return _ints["Rating", 0]; }

set { _ints["Rating", 0] = value; }

}

public bool? Married

{

get { return _bools["Married"]; }

set { _bools["Married"] = value; }

}

}

where ReferenceStock/ValueStock are:


public class ValueStock<Twhe re T : struct

{

private readonly Dictionary<stri ng, T_values;



public ValueStock()

{

_values = new Dictionary<stri ng, T>();

}



public T? this[string name]

{

get

{

if (_values.Contai nsKey(name))

return _values[name];



return null;

}

set

{

if (value.HasValue )

_values[name] = value.Value;

else

if (_values.Contai nsKey(name))

_values.Remove( name);

}

}

public T this[string name, T defaultValue]

{

get

{

return this[name] ?? defaultValue;

}

set

{

if (value.Equals(d efaultValue))

this[name] = null;

else

this[name] = value;

}

}
}
public class ReferenceStock< Twhere T : class

{

private readonly Dictionary<stri ng, T_values;



public ReferenceStock( )

{

_values = new Dictionary<stri ng, T>();

}



public T this[string name]

{

get

{

if (_values.Contai nsKey(name))

return _values[name];



return null;

}

set

{

if (value != null)

_values[name] = value;

else

if (_values.Contai nsKey(name))

_values.Remove( name);

}

}

}

The question is:

Do I have any chances to use the same name instead of ReferenceStock and ValueStock (like C++ templates allow to do in this situation)?

I just want to be able to write the following for every possible type of parameter:

private readonly FieldStock<stri ng_strings;

private readonly FieldStock<int_ ints;

private readonly FieldStock<bool _bools;

Thanks,
-- dmitry

[Jon Skeet [C# MVP]]

On Aug 19, 5:59*am, "Dmitry Nogin" <dmitry.no...@h otmail.comwrote :

I would like to use dictionaries to implement my property value storing mechanics.
(I have a lot but many of them are just about to keep <nullmost of the time, so it might save a lot of memory.)

<snip>

The question is:

Do I have any chances to use the same name instead of ReferenceStock and ValueStock (like C++ templates allow to do in this situation)?

Absolutely. All you really need is something like a
Dictionary<stri ng,T- and then use default(T) to find the appropriate
default value. It would be a lot simpler if you were happy to use
FieldStock<int? as then I supect you could get away without any
special-casing of value types in your code for FieldStock.

Jon

[Dmitry Nogin]

"Jon Skeet [C# MVP]" <sk***@pobox.co mwrote in message news:8e******** *************** ***********@79g 2000hsk.googleg roups.com...
On Aug 19, 5:59 am, "Dmitry Nogin" <dmitry.no...@h otmail.comwrote :

I would like to use dictionaries to implement my property value storing mechanics.
(I have a lot but many of them are just about to keep <nullmost of the time, so it might save a lot of memory.)

> The question is:
Do I have any chances to use the same name instead of ReferenceStock and ValueStock (like C++ templates allow to do in this situation)?

Absolutely. All you really need is something like a
Dictionary<stri ng,T- and then use default(T) to find the appropriate
default value. It would be a lot simpler if you were happy to use
FieldStock<int? as then I supect you could get away without any
special-casing of value types in your code for FieldStock.

Thanks.

I tried this, but in case of T==int? (which does not look so good, because of no constraints applicable here) - how can I expose property of original none-nullable type?

Can we provide generic "specialization s" (in c++ template understanding) anyhow?
-- dmitry

[Jon Skeet [C# MVP]]

On Aug 19, 1:18*pm, "Dmitry Nogin" <dmitry.no...@h otmail.comwrote :

"Jon Skeet [C# MVP]" <[e-mail] mwrote in messagenews:8e* *************** *************** ***@79g2000hsk. googlegroups.co m...
On Aug 19, 5:59 am, "Dmitry Nogin" <dmitry.no...@h otmail.comwrote :

I would like to use dictionaries to implement my property value storingmechanic s.
(I have a lot but many of them are just about to keep <nullmost of the time, so it might save a lot of memory.)

*The question is:
*Do I have any chances to use the same name instead of ReferenceStock and ValueStock (like C++ templates allow to do in this situation)?

Absolutely. All you really need is something like a
Dictionary<stri ng,T- and then use default(T) to find the appropriate
default value. It would be a lot simpler if you were happy to use
FieldStock<int? as then I supect you could get away without any
special-casing of value types in your code for FieldStock.

Thanks.

I tried this, but in case of T==int? (which does not look so good, because of no constraints applicable here) - how can I expose property of original none-nullable type?

At what point? If you could provide a short but complete program with
your current state of play, and what it is you don't have yet, that
would be helpful.

I would change the Rating property, for instance from:
return _ints["Rating", 0];
to
return _ints["Rating"] ?? 0;

At that point your dictionary class doesn't really have to know the
difference between nullable and non-nullable - and you'd be specifying
the defaults anyway.

Can we provide generic "specialization s" (in c++ template understanding) anyhow?

Not really, no. Generics in .NET are somewhat different to C++
templates.

Jon