call `[.data.table` explicitly
<p>I have a weird behavior, when running my R program on another machine.
When I try to run a data.table join <code>df1[df2]</code> I get the error message </p>

<blockquote>
  <p>Error in `[.default`(x, i) : invalid subscript type 'list'</p>
</blockquote>

<p>I assume that for some reason the R environment on the other machine does not find the data.table bracket function (Although I have loaded the library there).</p>

<p>To force R to use the bracket from data.table I would like to call the bracket function explicitly, but I can't find out how.</p>

<p>Here what I've tried</p>

<pre><code>library(data.table)    
df1 &lt;- data.frame(a = c("a1","a2","a3"), n = c(1,2,3), b = c(T,T,T))
df2 &lt;- data.frame(a = c("a1","a2","a3"), n = c(1,2,3), b = c(F,T,F))

df1 &lt;- data.table(df1)
df2 &lt;- data.table(df2)
setkey(df1,a,n,b)
setkey(df2,a,n,b)

df1[df2] # produces `[.default`(x, i) : invalid subscript type 'list'

# my tries to call `[.data.table` explicitly all produce errors
`[.data.table`(df1, df2)
data.table::`[.data.table`(df1, df2)
data.table::`[`(df1, df2)
</code></pre>

<p>How can I use the bracket function from the data.table package explicitly?</p>

<p><strong>EDIT:</strong></p>

<p>OK, I'm trying to find the root cause of the error.
I'm using R version 3.2.1,</p>

<pre><code>attached base packages:
[1] stats     graphics  grDevices utils     datasets  methods   base

other attached packages:
[1] data.table_1.9.2 mypackage_1.0    ROracle_1.1-10   DBI_0.2-7

loaded via a namespace (and not attached):
[1] plyr_1.8.1    reshape2_1.4  Rcpp_0.11.2   stringr_0.6.2
</code></pre>

<p><code>is.data.table</code> gives <code>TRUE</code> on both, df1 and df2 just before calling <code>df1[df2]</code> (I'm debugging through the code).</p>

<p>The function that contains the codeline <code>df1[df2]</code> is called inside mypackage_1.0 (A package I'm developing). I have noticed, that if I run the code line by line, instead of calling my package function and debugging it, the code works as expected. So I assume there is something wrong with the package. In the DESCRIPTION file I only import the package data.table under "Suggests". Might it be related to that?</p>