View Source ct_expand (parse_trans v3.4.2)
Compile-time expansion utility
This module serves as an example of parse_trans-based transforms, but might also be a useful utility in its own right. The transform searches for calls to the pseudo-function ct_expand:term(Expr)
, and then replaces the call site with the result of evaluating Expr
at compile-time.
For example, the line
ct_expand:term(lists:sort([3,5,2,1,4]))
would be expanded at compile-time to [1,2,3,4,5]
.
ct_expand has now been extended to also evaluate calls to local functions. See examples/ct_expand_test.erl for some examples.
A debugging facility exists: passing the option {ct_expand_trace, Flags} as an option, or adding a compiler attribute -ct_expand_trace(Flags) will enable a form of call trace.
Flags
can be []
(no trace) or [F]
, where F
is c
(call trace), r
(return trace), or x
(exception trace)'.
Summary
Types
-type abstract_expr() :: term().
-type form() :: any().
-type forms() :: [form()].
-type options() :: [{atom(), any()}].