You will see in the code I linked in the previous message that I already do
have the interfaces in there. They can't be bound to the struct directly
because I can't specify a function type that matches the signature, thus
the use of a wrapper, and the interface types in the parameters.
I just can't override them, and the great bulk of the code is not these
small set of initialiser/allocator/comparator/getter/setter functions, so
to have to search and replace through the whole thing, and maintain
multiple nearly identical pieces of source code for the sake of 7 functions
that are all very short, and differ between these versions, when everything
else is the same... then I find a bug in one version, in the outer shell of
the code and I have to merge every change of it into the other 5
versions... it's extremely cumbersome.
The solution I have shown is just the first thing that looks to me like it
would work. I have read tons of tutorials about composition and
polymorphism and embedding in go, and in the end I pieced this together
from several different things I learned. I tried several different things.
It just makes absolutely no sense to have to go through and add a load of
maintenance work to my code just so I can create, expand, read, write and
compare values stored within the otherwise identical data structure.
On Monday, 23 April 2018 01:44:43 UTC+3, matthe...@gmail.com wrote:
>
> Interface types are useful when the data structure is varied. Why not an
> interface containing these varying functions as methods instead of function
> types?
>
> Matt
>
> On Sunday, April 22, 2018 at 5:20:12 PM UTC-5, Louki Sumirniy wrote:
>>
>> I essentially am trying to find an effective method in Go, preferably not
>> too wordy, that lets me create an abstract data type, a struct, and a set
>> of functions that bind to a different data type, and that I can write,
>> preferably not in too much code, a change that allows the data type of the
>> embedded data to be changed. It's basically kinda inheritance, but after
>> much fiddling I found a hackish sorta way that isn't *too* boilerplate
>> filled:
>>
>> type nullTester func(*Bast, uint32) bool
>>
>> type Bast struct {
>> ...
>> isNull nullTester
>> ...
>> }
>>
>> func isNull(b *Bast, d uint32) bool {
>> return d == 0
>> }
>>
>> func NewBast() (b *Bast) {
>> ...
>> b.isNull = isNull
>> ...
>> }
>>
>> // IsNull - tests if a value in the tree is null
>> func (b *Bast) IsNull(d uint32) bool {
>> return b.isNull(b, d)
>> }
>>
>>
>> Now, bear in mind I haven't shown all of the code. But there is a slice
>> array in the Bast struct, and I it is defined as an interface{} and isNull
>> is one of a set of operators that have to be written to match the type used
>> in the slice store, this might be a bad example because it doesn't actually
>> act on the interface typed slice, but the point here is just this:
>>
>> It does not appear to be possible to make the type specification from the
>> top line match the function signature of the type-bound function in the
>> bottom of the code snippet. I haven't been able to find anything that shows
>> that a func type can have a method binding.
>>
>> https://github.com/calibrae-project/bast/blob/master/pkg/bast/bast.go is
>> where my WiP lives. This slightly hacky solution seems sound to me, I just
>> don't like to be forced to use workarounds like this. If a type signature
>> cannot be written that matches a method, yet I can do it this way, I don't
>> see what purpose this serves as far as any kind of correctness and
>> bug-resistance issues go. I would have to deal with a lot more potential
>> bugs if I had to concretely implemennt this library for the sake of 1 slice
>> and 7 functions out of a much larger library that conceptually is intended
>> to only deal with comparable, mainly numerical values anyway.
>>
>
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