Collection of warning flags used when traversing expressions.

These are flags for turning warnings on or off when traversing expression trees.

warning_flags()

set_warn_on_unknown_function(flags)

unset_warn_on_unknown_function(flags)

set_warn_on_local_function(flags)

unset_warn_on_local_function(flags)

Arguments

flags	Used when setting or unsetting flags.

Details

The flags can be provided to transformation and analysis functions, and be set or unset by the set_/unset_ functions. The meaning of the flags are:

• warn_on_unknown_function: If you have installed a callback with add_call_callback() or add_topdown_callback(), the traversal code will check if a given call is to a known function installed by one of these. If the function name of a call is not recognised as a function parameter or a local variable, as annotated with annotate_bound_symbols_in_function(), then the code will issue a warning if this flag is set. The warning behaviour depends on whether annotate_bound_symbols_in_function() has analysed the function. If it hasn't, then we only consider function parameters as local variables. If it has, we have more information about the local variables, so we can make the warnings more accurate. The flag is set by default.

• warn_on_local_function: If you have installed a callback with add_call_callback() or add_topdown_callback(), the traversal code will check if a given call is to a known function installed by one of these. If you have installed a function that has a name-clash with a local variable, and this flag is set, then you will get a warning. If you have annotated the expression tree using annotate_bound_symbols_in_function(), then the warning will be invoked both on local variables and function parameters; if you have not annotated the expression tree, then it will only be invoked on function arguments. The flag is set by default.

Since R is a very dynamic language, it is not possible to know which local variables might refer to functions and which do not -- and R will look for functions if a variable is used as a call and potentially skip past a local variable that refers to a non-function -- so the warnings are based on heuristics in identifying local variables and are conservative in the sense that they assume that if a call is to a name that matches a local variable, then it is the local variable that is being called.

Functions

• set_warn_on_unknown_function: Enable warnings when encountering an unknown function

• unset_warn_on_unknown_function: Disable warnings when encountering an unknown function

• set_warn_on_local_function: Enable warnings when encountering a local variable with a name that matches one installed for transformation.

• unset_warn_on_local_function: Disable warnings when encountering a local variable with a name that matches one installed for transformation.