From 1f39d4148e588a5476e96550591131ae65ad0fe2 Mon Sep 17 00:00:00 2001 From: John Wiegley Date: Sat, 21 Feb 2009 18:49:43 -0400 Subject: Create a new interactive_t helper class The purpose of this class is much like Emacs' (interactive) form: it allows a value expression function to declare exactly how many arguments, and of what type, it intends to receive. It then offers type-safe access to theese arguments in a consistent manner. An example value expression function definition in C++: value_t fn_foo(call_scope_t& scope) { // We expect a string, an integer, and an optional date interactive_t args(scope, "sl&d"); std::cout << "String = " << args.get(0) << "Integer = " << args.get(1) << std::endl; if (args.has(2)) // was a date provided? std::cout << "Date = " << args.get(2) << std::endl; return NULL_VALUE; } There is also an in_context_t template, which finds the context type T in the current scope hierarchy. The in_context_t then also acts as a smart pointer to reference this context object, in addition to serving the same duty as interactive_t. This combination of intent is solely for the sake of brevity. value_t fn_bar(call_scope_t& scope) { in_context_t env(scope, "sl&d"); std::cout << "Account name = " << env->fullname() << "String arg = " << env.get(0) << std::endl; return NULL_VALUE; } As you can see here, 'env' acts as a smart pointer to the required context, and an object to extract the typed arguments. --- src/precmd.cc | 1 + 1 file changed, 1 insertion(+) (limited to 'src/precmd.cc') diff --git a/src/precmd.cc b/src/precmd.cc index c02be263..4b623904 100644 --- a/src/precmd.cc +++ b/src/precmd.cc @@ -30,6 +30,7 @@ */ #include "precmd.h" +#include "interactive.h" #include "report.h" namespace ledger { -- cgit v1.2.3