RE: Intercept function call
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- Subject: RE: Intercept function call
- From: RLake@...
- Date: 2003年10月22日 16:18:46 -0500
> In another different file I should have one list (I still don't know how
> to make this list. It has to be in a generic way to be used for any
> program just changing the list) of the functions that I want to
intercept
> (for example, the query and remove). Before or after the execution of
> them, it must execute the function logging and then return to execute
the
> next function.
You will want to use the "reflexive debug interface", as described
in the manual. Set a hook function to intercept on call and return, and
then try to identify the function that is being intercepted.
If your functions are globals, it is not too difficult.
eg:
do
local intercepts = {}
function intercept(f, on)
local rv = intercepts[f]
intercepts[f] = on
return rv
end
local hookstack = {n = 0}
local function callhook()
local f = debug.getinfo(3, "f").func
table.insert(hookstack, f)
if intercepts[f] then doOnCall(f) end
end
local function rethook()
local f = table.remove(hookstack)
if intercepts[f] then doOnReturn(f) end
end
local case = {
["call"] = callhook,
["return"] = rethook,
["tail return"] = rethook
}
local function nothing() end
local function myhook(what)
(case[what] or nothing)()
end
debug.sethook(myhook, "cr")
end
-- define doOnCall and doOnReturn to do whatever
-- to intercept a function:
function foo(a) print "foo" end
intercept(foo, true)
-- to intercept a function given its name (if it is a global)
a = "foo"
intercept(getfenv()[a], true)
-- I hope the above code is easy to follow.
-- Quick test:
> function doOnCall(func) print "An intercepted call" end
> function doOnReturn(func) print "An intercepted return" end
> foo(3)
An intercepted call
foo
An intercepted return
>