Thoughts on importing names from modules into a namespace
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- Subject: Thoughts on importing names from modules into a namespace
- From: Chris Marrin <chris@...>
- Date: 2006年4月25日 13:10:06 -0700
I have been thinking about the idea of importing names, like what python
does with its various flavors of import statement. This goes along with
requiring modules that do not put themselves into the global namespace.
My requirements are this. I want to be able to require a module and then
import some or all of the properties in that module into a given
namespace. These names could import with the same name as in the module,
or they could use a common prefix to the module name, or could use a
completely different name. For simplicity, I only want to import
function properties. Here is what I came up with:
function import(ns, mod, map)
-- if we don't pass in a ns, use the fenv of the caller
if ns == nil then
ns = getfenv(2)
end
-- if map is a string, it is the prefix for every function
local prefix = ""
if type(map) ~= "string" then
prefix = map
map = { }
elseif type(map) ~= "table" then
map = { }
end
-- refactor map
local newmap = { }
for k,v in pairs(map) do
if type(k) == "number" then
newmap[v] = v
elseif type(k) == "string" then
newmap[k] = v
end
end
-- import
local all = #newmap == 0
for k,v in pairs(mod) do
if type(v) == "function" then
local key = newmap[v]
if key == nil then
if all then
key = k
end
end
if key ~= nil then
self[prefix..key] = v
end
end
end
end
This allows you do do the following:
import(nil, require "Node3D", { MyShape = "Shape", "Group" }
If the 'ns' param is nil, we use the fenv of the function containing the
import statement. If none is set, this will put the imported names into
the global object. In this example, only two functions from the module
are imported: "Shape" (which is renamed to "MyShape") and "Group".
I can also go:
import(nil, require "Node3D")
to import everything, or:
import(nil, require "Node3D", "my_")
to import everything and prefix each function name with "my_".
I think this gives pretty much all of the functionality I know about in
Python's import statement.
Any comments???
--
chris marrin ,"",ドル
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"As a general rule,don't solve puzzles that open portals to Hell"'