[JW Lua] RFC: Adding Methods/Properties to RGP Lua that only exist in certain Finale versions

Wed Aug 24 17:51:19 CEST 2022

I have been experimenting with throwing an error out of C++ this morning,
and it works seamlessly exactly as one would hope. I much prefer an error
message that says, "modula.lua line 420: Finale 26.9 required". (To make up
a Finale version.)

Plus, you'll only have to use pcall if you are unwilling to specify
MinFinaleVersion in your plugindef.

On Wed, Aug 24, 2022 at 10:26 AM Nick Mazuk <nick at nickmazuk.com> wrote:

> Throwing an error might be redundant. For instance, if the following
> prints out nil (for instance, if the method doesn't exist on the object):
>
> local entry = finale.FCEntry()
> print(entry.FooBar)
>
> then the following will already be thrown an error since nil is not a
> function:
>
> local entry = finale.FCEntry()
> entry:FooBar() — error!
>
> The only advantage I can think of by having RGP Lua throw an error if you
> even access it is that you'll potentially get more meaningful error
> messages as a user. As a developer, the plugin will still tell you exactly
> what line of code threw the error. However, it has the disadvantage that
> you must use pcall to capture the error and you cannot simply check if the
> method exists or not (which developers should be doing anyways for any
> newly added features to RGP Lua).
>
>
> On Wed, Aug 24, 2022 at 5:24 AM, Robert Patterson <
> robert at robertgpatterson.com> wrote:
>
>> Throwing an error is a good idea that I hadn't thought of. However, these
>> errors would have to be thrown out of the PDK Framework, which is not Lua.
>> So far, there is no try/catch/throw in the PDK Framework codebase. That is
>> not to say we couldn't start using it, but it will require approvals from
>> the other clients that share that code.
>>
>> Meanwhile, if the function is missing you'll get the same behavior. It
>> just won't have as helpful an error message. And by leaving it missing, you
>> don't have to resort to pcall. You can simply test if it is there.
>>
>>
>> On Wed, Aug 24, 2022 at 6:18 AM Daniel Grunwald <dgr at leng.de> wrote:
>>
>>> Hi there,
>>>
>>> it seems my first reply didn't get through. So I repeat it. I case you
>>> receive this twice you know why.
>>>
>>> I am a lua novice having no actual experience in lua so my idea might be
>>> foolish. However from what I learned in terms of clean code in other
>>> languages I would prefer to raise an error instead of not providing the
>>> function.
>>> In order to deal with this users will have to use pcall, as described in
>>> https://www.lua.org/pil/8.4.html
>>>
>>> Although not knowing if it really is (by lack experience) to me it
>>> sounds like a cleaner approach.
>>>
>>> However if you like to use the nil-approach I suggest putting "OrNil" as
>>> suffix to the function's name so the name indicates it possibly being nil.
>>>
>>> Hope this was helpful.
>>>
>>> Best regards
>>> Daniel
>>>
>>> Von meinem Xperia[image: ™] von Sony-Smartphone gesendet
>>>
>>>
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>>> Today's Topics:
>>>
>>>    1. RFC: Adding Methods/Properties to RGP Lua that only exist in
>>>       certain Finale versions (Robert Patterson)
>>>
>>>
>>> ----------------------------------------------------------------------
>>>
>>> Message: 1
>>> Date: Mon, 22 Aug 2022 15:03:15 -0500
>>> From: Robert Patterson <robert at robertgpatterson.com>
>>> To: "The JW Lua script plug-in." <jwlua at jwmusic.nu>
>>> Subject: [JW Lua] RFC: Adding Methods/Properties to RGP Lua that only
>>> exist in certain Finale versions
>>> Message-ID:
>>> <CAACnceu23XaymU4XNBZQ-1e6wDdP5xP6-ht8fdk3trUduahrUA at mail.gmail.com>
>>> Content-Type: text/plain; charset="utf-8"
>>>
>>> I will soon be adding to RGP Lua some methods and properties that are not
>>> available before a certain Finale version. Previously when this has
>>> happened, the methods and properties appear in all Finale versions but
>>> return a default value in earlier Finale versions where they aren't
>>> supported. Until now there has always been an appropriate default value.
>>>
>>> However, these new methods and properties I plan to add do not have
>>> useful
>>> default values in earlier Finale versions. In fact, it would be a bad
>>> idea
>>> to return anything at all unless running in an supported Finale version.
>>>
>>> To me the best solution would appear to be not to hook up these methods
>>> and
>>> properties to Lua if the Finale version doesn't support them. But that
>>> means, in perpetuity, Lua programmers will have to check them for `nil`
>>> before calling them. Does anyone have other/better ideas?
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