instantiate classes

[sane1111]

Hello, everyone,

with regard to NT, some questions arise.

Why is it possible in NT to call a class and use it like a method. Why doesn't it need to be instantiated. When does a class need to be instantiated? in C# always unless it is static.

Example:

protected override void OnBarUpdate()
{
if(MAX(High, 10)
dosomething
}


Thank you for your answers.

[bltdavid]

Why is it possible in NT to call a class and use it like a method.

This is all supplied by the automatically generated 'magic code' seen
at the bottom of each indicator.

Studying the magic code in NT7 was much more straightforward, the
newer NT8 magic code techniques have definitely hidden more details.

[bltdavid]

C# allows a method name to be same name as a class name.
Yep, that's not a loophole, that's a design feature built directly
into the C# language specification.

That is,
the basis of the 'magic' is the auto generated code that does this,

public EMA EMA(int period)
{
    return EMA(Input, period);
}

public EMA EMA(ISeries<double> input, int period)
{
    ....
}

To wit --

You (or in this case, the NT developers) define a class
named EMA, which uses 'Indicator' as it's base class.
This is the 'user' code.

The auto generated code defines methods named EMA,
which are (by design) the same name as the class name
you defined. The auto generated code is created by the
NinjaScript compiler.

The method named 'EMA' is returning an object reference
to a class named 'EMA' -- don't get the class and the method
confused -- being able to read the code well is extremely
critical here, context is key.

Note that two methods named 'EMA' are defined,
this is an example of method overloading.

The magic code is all very cool stuff, and all very
undocumented.

And, yes, the EMA method essentially performs a 'new'
to instantiate an object of class EMA, but checks the cache
of previous EMA objects and returns a matching reference
if the arguments were identical.

That is, the EMA method first checks the cache, and if a
matching reference is not found, it calls new to create a
new reference, adds that to the cache, and then returns
that reference.

The return reference must be properly 'marinated' by adding
it to various internal lists -- for ex, the object's methods
such as OnStateChange, OnBarUpdate, et al, must be
called by the NinjaTrader internals at the appropriate
times. Again, all very undocumented.

The auto generated magic code definitely exploits the
object oriented power of the C# language.

[NinjaTrader_Kate]

Hello sane1111,

Thank you for your post.

bltdavid has pretty much nailed it here, so there's not a lot I'd add. Basically yes, it's the magic code at the bottom that gets generated by NinjaTrader when you compile that's making that magic happen, which is not documented.

Please let us know if we may be of further assistance to you.