Added feature for processing nested structures

[msfur]

Enables processing for nested structures, as mentioned in and fixes #308 and on Stackoverflow. Takes into account nested structures in the following form:

    substructure_def = (
         ("iVar", pyads.PLCTYPE_INT, 1),
         ("sVar", pyads.PLCTYPE_STRING, 1)
     )

    structure_def = (
         ("iVar1", pyads.PLCTYPE_INT, 1),
         ("structVar", substructure_def, 2)
     )

or

    structure_def = (
        ("iVar1", pyads.PLCTYPE_INT, 1),
        ("structVar",
            (
                ("iVar", pyads.PLCTYPE_INT, 1),
                ("sVar", pyads.PLCTYPE_STRING, 1)
            ), 2
        )
    )

Contains adaptations to size_of_structure(), dict_from_bytes() and bytes_from_dict() and the associated tests.

[coveralls]

Pull Request Test Coverage Report for Build 10633564917

Details

• 9 of 9 (100.0%) changed or added relevant lines in 1 file are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage increased (+0.03%) to 94.951%

---

Totals
Change from base Build 10631185064:	0.03%
Covered Lines:	1730
Relevant Lines:	1822

---

💛 - Coveralls

[chrisbeardy]

@msfur this is awesome, looks great as a solution for the nested structs issue and thanks for adding the tests in too! If possible, could you please add a documentation example at the end of this section too? https://pyads.readthedocs.io/en/latest/documentation/connection.html#structures-with-multiple-datatypes

I will then merge.

[msfur]

@chrisbeardy I have made the desired change to the documentation and added an example.

[keenanjohnson]

This looks great! Any way I can support getting this merged?

[kryskool]

Hi @msfur
I validate this merge request with my tests (pytest) for my hospital cabinet, and nested structure works perfectly

This PR is ok for me (must be rebase)

[kryskool]

Nested Structure works (test also with TIMESTRUCT)

[msfur]

Hi @kryskool,
thanks for the approval. I have rebased the branch as requested.

[kryskool]

@chrisbeardy this PR is ok for merging

[chrisbeardy]

thanks all for this, will release new version soon, couple of other PRs to merge

[chrisbeardy]

@msfur thanks for the contribution, this is a great edition to pyads. Since you've wetted your palette now with this PR, theres a open issue related to structs in #289 if you wanted to have a look and this is relevant to helping with your workflow.

[keenanjohnson]

Great work getting this merged in all! I know I'm just a random person on the internet, but working together like this on software that most people will never hear about is truly useful for hummanity and I appreciate you. - Some random user of pyads

[msfur]

@msfur thanks for the contribution, this is a great edition to pyads. Since you've wetted your palette now with this PR, theres a open issue related to structs in #289 if you wanted to have a look and this is relevant to helping with your workflow.

I'm going to check it out and see if there's anything I can contribute.

[tom-ils]

@msfur thanks for this great feature- I have been working with your branch of pyads for a few months now so great to see it merged into master