Another issue with R-base functions that check for missingness of arguments without default values.

[swang87]

Example:

tmp <- fc(ls, all.names = TRUE)
tmp() 

This fails but the following works:

ls(all.names=TRUE)

Basically, when tmp() is run, R complains that pattern cannot be found. Within the ls() function, we can see that there are conditional clauses that check for whether the pattern argument is passed in.

[swang87]

Turns out problem is that pattern (no defaults) follows a large number of arguments with defaults in ls().

Add a .missing argument in fc(), so that we can say fc(ls, .missing = "pattern") so that we explicitly omit arguments from function signature.