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I have a method with quite a few local variables, and I would like the option to assign/modify a certain subset of these local variables. As an example, instead of having a block of code

x=a; y=b; …

etc. repeatedly at certain points in the method, I'd like to just have some function that would assign these values, so in the above I would just call f(a,b,...). The assignment might be a bit more complicated though - I might be using values from certain arrays, some variables might not be incremented by a fixed value, etc.

Is there some way to do this neatly? What are some good options? Maybe I should work with a struct that contains all those variables? Or I could just declare a function where I will pass a reference to all the variables, and also the values. Ideally, I would like to declare some sort of method that will implicitly know all the local variables of the method I'm currently in. However, my only goal is to make the code easier to read - the method won't be used anywhere else, so theoretically I'd be fine if the compiler just directly translates f(a,b,...) into the assignment code x=a;y=b;…

Does my problem maybe signify bad practice, and that I'm doing things wrong? Maybe I shouldn't be using these variables as local in the first place if I want do things like this with them - instead they could be member fields of a class. Then I could define a method that would do such assignments without problems.

EDIT - for more context on the problem: my intention is to create a mesh-slicing method. Assuming the slicing plane is fixed, the arguments of this slice method are structs that are composed of arrays of various attributes of the mesh - each such struct contains the vertex attributes (positions, normals etc.), triangle indices, and the sizes of those respective arrays. Into the Slice method I pass three such structs - one as the input, and the other two for the upper and lower part of the resulting slice.

Since all the vertices, normals etc of the input will be processed, there could be a lot of them, and I'm hoping for maximal efficiency (the purpose of this mesh slicer is real-time mesh slicing in Unity), I cache all of these as local variables (to avoid dereferencing the argument struct all the time). This might be a big mistake and a case of overly early optimization. But I wanted to try it, since I would have probably tried it later anyway to see if it helps. Now as I'm processing the vertices of the input mesh, if I find that I should add the vertex into the upper/lower mesh, I check if I've already done so, and if not, I add it, and also set all the normals etc. Here is the code for "processing" a triangle of the input mesh that has been deemed as lying above the slicing plane, and is to be added to the upper mesh.

currentlyProcessedIndices[j] is the index of the jth point of the current triangle (index in the vertex array of the input mesh).