Set 2 structure fields to be the same result when 1 is a function call within a structure element

Hello all,

Kind of long winded here, but im just trying to explain myself as best i can. My need, issue, rational, etc.

I am using matlab to interface to a hardware device, I am trying to formulate the most convienient method to structure the commands list, which right now seems to be by building a strucure where i segregate commands based on which device they are a part of etc.

Ex:

A.B.C1 = @(x,y) Test(x,y)

Is a command C1, associated with hardware device A submodule B

The structure doesnt hold the communication protocol directly, but rather address/instructions for a particular port.

Here simulated by variables X and Y which are sent to the simulated communication function "Test" to completed the coms connection and get the data value.

Its important to note that there are hundreds of "Commands" which i can issue to the same communication function.

So I need to keep the communication function as general as possible.

Due to the actual communication function generating a network load, there are instances where i dont need to actually open a coms port to get a data value, and would rather just utilize a stored value from a previous call.

But... every. single. time. that i want to open a communication port to get a value I dont want to have to write a seperate line of code to assign the value back to the structure.

Ex:

CallOutput = A.B.C2(X,Y) %Induces the network load, gather the data from the hardware device
A.B.C1     = CallOutput  % this the line of code is what i am trying to avoid needing to do everysingle time i need to communicate
%Do other things
value      = A.B.C1      %reading the stored value from the structure at some later time

So, I would really like it. If when i perform the communication call

A.B.C2(X,Y)

It automatically assigned the output to the

A.B.C1

structrure element as well, while also allowing me to assign that value to a seperate variable.

I thought i could use the deal() function to make this work.

But it just seems to pass the function handle to A.B.C1 instead of the value. which makes sense

X = 1
Y = 2
[A.B.C1,A.B.C2] = deal(@(x,y) Test(x,y));
CallOutput = A.B.C2(X,Y)
value      = A.B.C1

function [Z]=Test(X,Y)
    Z=X+Y;
end

Does anyone know of a way to get a structure function to perform its task and output a value, while also assigning that value to another structure element?

I recognize this as a way to go about things, bascially use deal to make the assignment when calling that structure function

X = 1
Y = 2

A.B.C2 = @(x,y) Test(x,y);

[CallOutput,A.B.C1] = deal(A.B.C2(X,Y))

CallOutput
value      = A.B.C1


function [Z]=Test(X,Y)
    Z=X+Y;
end

But it just seems like there should be a way to get the assigment to occur within the actual comunication event portion of the code directly, thus eliminating addittional code that i just cant figure out.

A.B.C2 = @(x,y) Test(x,y);

Thoughts?

[Voss]

Why not just this?

A.B.C1 = A.B.C2(X,Y);

And then refer to A.B.C1 if you want to use that value for something else.

[John H.]

Yup Yup, i can certianly do that. But i am trying to avoid the neccessity of having 2 lines of code for every one data call. If its not possible then sure ill do what i have to do. But I am really hoping that someone smarter than I knows the solution.

Think of my objective as having a command set, i call 1 command by typing the structure CallOutput = A.B.C2(X,Y)

Then sometime later, a completely different portion of the code, maybe not even the same function, i pass structure A, call A.B.C1 and get that value again without needing to push a data call to the hardware for it.

It becomes super annoying to instead need to do this every time.

CallOutput = A.B.C2(X,Y);

A.B.C1 = A.B.C2(X,Y);

There has to be a sneaky way to embedd that command into the

A.B.C2 = @(x,y) Test(x,y); code in the backend.

Maybe there is a completely better way to do this that doesnt use the structure topology, i dont know but im all ears.

Answer 1

[Jan]

You can use memoize or a simple tool like here: https://www.mathworks.com/matlabcentral/answers/1892960-memoize-save-restore-cache#answer_1148125

This calls the function once only and copies the result from the cache in the next call.