[datatable-help] Using := in .onLoad

[Juan Manuel Truppia]

Let's follow an example. I'm developing my own package. I add data.table to
imports in my description file. This means I have to use the :: operator
each time I want to call a data.table function.  Can I use := in this setup?

On Tue, Jan 20, 2015, 10:01 Arunkumar Srinivasan <aragorn168b at gmail.com>
wrote:

> Juan,
>
>>
>> I already know that.
>>
> Okay, great.
>
>> I usually struggle when using data.table inside my own packages. I start
>> by listing it in imports only (and not importing anything)
>>
> "imports only (and not importing anything)"?  - what do you mean?
>
>> but end up depending on it, as for the users to be able to manipulate the
>> data.tables with [ and :=.
>>
> It depends on whether you want the data.table NAMESPACE to be attached or
> not. I think these posts may help:
>
> http://r.789695.n4.nabble.com/Re-R-CMD-check-checking-in-development-version-of-R-td4696125.html#none
>
> http://stackoverflow.com/questions/8637993/better-explanation-of-when-to-use-imports-depends
>
>
>> I end up importing some or all of data.table also, because I don't know
>> how to call := the :: notation.
>>
> I don't really follow this. Why do you want to use `::` along with `:=`.
> The last post we just discussed that it can't be done, as it is not
> designed to be used outside of  `[...]` and in very specific ways. Check
> data.table:::`:=`. It is designed to error. This post might help:
> http://stackoverflow.com/q/7033106/559784
>
>> My specific problem was on using := during on.Load.
>>
> It'd be useful to know what you are trying to do, along with your code.
>
>> I already know how to use it, and know that it can only be used inside [.
>> Maybe it is imperative to @import data.table to be able to use :=?
>>
> I don't follow exactly how you are trying to use := to answer this.
>
> Arun
>
>>
>> On Mon, Jan 19, 2015, 19:35 Arunkumar Srinivasan <aragorn168b at gmail.com>
>> wrote:
>>
>>> Within the square brackets in "DT[ .... ]" and even there, only in `j`
>>> (as the error message points out).
>>>
>>> On Mon, Jan 19, 2015 at 11:31 PM, Juan Manuel Truppia <
>>> jmtruppia at gmail.com> wrote:
>>>
>>>> Arun, what does "within the frame of data.table" mean?
>>>>
>>>> On Mon, Jan 19, 2015, 19:17 Arunkumar Srinivasan <aragorn168b at gmail.com>
>>>> wrote:
>>>>
>>>>> Juan,
>>>>>
>>>>> `:=` is designed to be used only within the frame of data.table.
>>>>>
>>>>> On Mon, Jan 19, 2015 at 10:45 PM, Juan Manuel Truppia <
>>>>> jmtruppia at gmail.com> wrote:
>>>>>
>>>>>> Hi, I'm using data.table inside my own packages. I'm having some
>>>>>> trouble using data.table functions on my .onLoad method.
>>>>>> I'm actually depending (not importing) data.table, but even then, I
>>>>>> can't get := to work in .onLoad.
>>>>>> I'm using the `:=`(a = x, b = y) version, and getting
>>>>>>
>>>>>> Error in `:=`(a = x) :
>>>>>> Check that is.data.table(DT) == TRUE. Otherwise, := and `:=`(...) are
>>>>>> defined for use in j, once only and in particular ways. See help(":=").
>>>>>>
>>>>>> If I comment that, and then run it from the console after the package
>>>>>> is loaded, it works.
>>>>>>
>>>>>> Any ideas?
>>>>>>
>>>>>> _______________________________________________
>>>>>> datatable-help mailing list
>>>>>> datatable-help at lists.r-forge.r-project.org
>>>>>>
>>>>>> https://lists.r-forge.r-project.org/cgi-bin/mailman/listinfo/datatable-help
>>>>>>
>>>>>
>>>>>
>>>
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