Quick Indexers Q and a bit more...

[Picho]

Hi everyone.

Is it possible to decalre a static indexer to a class?
obviosly not, because the 'this' keyword is not valid when declaring it
static...
so how can I get a similar result of an indexer WITHOUT using accessor
methods like
static object GetObject(int index){...}
and
static void SetObject(int index, object value){...}
?

another question:
lets say i have a class:
public class ClassA
{
private object _value;

public ClassA()
{
}
public object Value
{
get{...}
set{...}
}
}

Can I cause one of the class properties to be a ... lets say default
property?
so I can write something like:

ClassA c = new ClassA();
c = null;
//instead of:
c.Value = null;

I know this looks twisted and silly, but i would realy like to try this -
skipping the property access stage (the property type is an object and thats
a given).
I tried creating an implicit conversion to and from 'object' which looked
like the right direction to me but then I got a compiler error that says I
cant cast from a base class (since ClassA derives from object naturally..)

smart compiler. silly me.

anyways,
can I do this in some manner or is it hopeless?

thanx alot,

Picho

 

[Jon Skeet [C# MVP]]

Is it possible to decalre a static indexer to a class?

Unfortunately not.

obviosly not, because the 'this' keyword is not valid when declaring it
static...
so how can I get a similar result of an indexer WITHOUT using accessor
methods like
static object GetObject(int index){...}
and
static void SetObject(int index, object value){...}
?

You can't, I'm afraid.

another question:
lets say i have a class:
public class ClassA
{
private object _value;

public ClassA()
{
}
public object Value
{
get{...}
set{...}
}
}

Can I cause one of the class properties to be a ... lets say default
property?
so I can write something like:

ClassA c = new ClassA();
c = null;
//instead of:
c.Value = null;

No - thank goodness. That would be *very* confusing, causing really
unreadable code. How would you change or access the actual value of c
rather than that of c.Value?

I know this looks twisted and silly, but i would realy like to try this -
skipping the property access stage (the property type is an object and thats
a given).

Could I ask why? What's the benefit here?

I tried creating an implicit conversion to and from 'object' which looked
like the right direction to me but then I got a compiler error that says I
cant cast from a base class (since ClassA derives from object naturally..)

smart compiler. silly me.

anyways,
can I do this in some manner or is it hopeless?

I don't believe you can do it.

 

[Picho]

Hi Jon, thanx for the reply.

it is unfortunate that we cannot set a static indexer....

the benefit of the other issue is... well simply much more clear code even
though i stated it seems twisted and silly for the same reasons you said and
therefor this question was doomed to start with so we might as well just
forget it

since you asked:

I am trying to write a class that will encapsulate application-wide
variables (very much like the session object in asp). for that I could use a
simple sorted list or other ADT. I wanted to add support for change events
for these variables. this means that the objects in the list are not the
actual variable values but other objects that i created. my goal was to be
able to write this:

//(Session is static)
Session["var1"] = true;
Session["var2"] = new string[] {"bla", "bla"};
Session["var2"].Change+=new EventHandler(var2_Change);

this will explain:
1. static indexer
2. twisted silly assignment

any suggestions?

Picho

 

[Jon Skeet [C# MVP]]

it is unfortunate that we cannot set a static indexer....
Agreed.

the benefit of the other issue is... well simply much more clear code even
though i stated it seems twisted and silly for the same reasons you said and
therefor this question was doomed to start with so we might as well just
forget it

since you asked:

I am trying to write a class that will encapsulate application-wide
variables (very much like the session object in asp). for that I could use a
simple sorted list or other ADT. I wanted to add support for change events
for these variables. this means that the objects in the list are not the
actual variable values but other objects that i created. my goal was to be
able to write this:

//(Session is static)
Session["var1"] = true;
Session["var2"] = new string[] {"bla", "bla"};
Session["var2"].Change+=new EventHandler(var2_Change);

this will explain:
1. static indexer
2. twisted silly assignment

any suggestions?

Well, you could make Session a singleton, and use

Session.Instance["var1"] = true;

or use

Session session = Session.Instance;
x["var1"]=true;
x["var2"]=true;

etc

I personally don't like the last bit of syntax, preferring:

Session.Change["var2"]+=new EventHandler(...);

However, getting that to work would be somewhat tricky too. I suggest
you just have:

Session.AddChangeHandler ("var2", new EventHandler(...));

Not quite as nice, but gets the job done.

 

[Picho]

well,
nice is what its all about

thanks.

it is unfortunate that we cannot set a static indexer....
Agreed.

the benefit of the other issue is... well simply much more clear code even
though i stated it seems twisted and silly for the same reasons you said and
therefor this question was doomed to start with so we might as well just
forget it

since you asked:

I am trying to write a class that will encapsulate application-wide
variables (very much like the session object in asp). for that I could use a
simple sorted list or other ADT. I wanted to add support for change events
for these variables. this means that the objects in the list are not the
actual variable values but other objects that i created. my goal was to be
able to write this:

//(Session is static)
Session["var1"] = true;
Session["var2"] = new string[] {"bla", "bla"};
Session["var2"].Change+=new EventHandler(var2_Change);

this will explain:
1. static indexer
2. twisted silly assignment

any suggestions?

Well, you could make Session a singleton, and use

Session.Instance["var1"] = true;

or use

Session session = Session.Instance;
x["var1"]=true;
x["var2"]=true;

etc

I personally don't like the last bit of syntax, preferring:

Session.Change["var2"]+=new EventHandler(...);

However, getting that to work would be somewhat tricky too. I suggest
you just have:

Session.AddChangeHandler ("var2", new EventHandler(...));

Not quite as nice, but gets the job done.

 

[Picho]

b.t.w:

could you explain 'singleton'?

thanks

it is unfortunate that we cannot set a static indexer....
Agreed.

the benefit of the other issue is... well simply much more clear code even
though i stated it seems twisted and silly for the same reasons you said and
therefor this question was doomed to start with so we might as well just
forget it

since you asked:

I am trying to write a class that will encapsulate application-wide
variables (very much like the session object in asp). for that I could use a
simple sorted list or other ADT. I wanted to add support for change events
for these variables. this means that the objects in the list are not the
actual variable values but other objects that i created. my goal was to be
able to write this:

//(Session is static)
Session["var1"] = true;
Session["var2"] = new string[] {"bla", "bla"};
Session["var2"].Change+=new EventHandler(var2_Change);

this will explain:
1. static indexer
2. twisted silly assignment

any suggestions?

Well, you could make Session a singleton, and use

Session.Instance["var1"] = true;

or use

Session session = Session.Instance;
x["var1"]=true;
x["var2"]=true;

etc

I personally don't like the last bit of syntax, preferring:

Session.Change["var2"]+=new EventHandler(...);

However, getting that to work would be somewhat tricky too. I suggest
you just have:

Session.AddChangeHandler ("var2", new EventHandler(...));

Not quite as nice, but gets the job done.

 

[Jon Skeet [C# MVP]]

b.t.w:

could you explain 'singleton'?

See http://www.pobox.com/~skeet/csharp/singleton.html