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Diffstat (limited to 'class.lua')
| -rw-r--r-- | class.lua | 250 |
1 files changed, 0 insertions, 250 deletions
diff --git a/class.lua b/class.lua deleted file mode 100644 index d260c31..0000000 --- a/class.lua +++ /dev/null @@ -1,250 +0,0 @@ ---- Provides a reuseable and convenient framework for creating classes in Lua. --- Two possible notations: --- --- B = class(A) --- class.B(A) --- --- The latter form creates a named class within the current environment. Note --- that this implicitly brings in `pl.utils` as a dependency. --- --- See the Guide for further @{01-introduction.md.Simplifying_Object_Oriented_Programming_in_Lua|discussion} --- @module pl.class - -local error, getmetatable, io, pairs, rawget, rawset, setmetatable, tostring, type = - _G.error, _G.getmetatable, _G.io, _G.pairs, _G.rawget, _G.rawset, _G.setmetatable, _G.tostring, _G.type -local compat - --- this trickery is necessary to prevent the inheritance of 'super' and --- the resulting recursive call problems. -local function call_ctor (c,obj,...) - -- nice alias for the base class ctor - local base = rawget(c,'_base') - if base then - local parent_ctor = rawget(base,'_init') - while not parent_ctor do - base = rawget(base,'_base') - if not base then break end - parent_ctor = rawget(base,'_init') - end - if parent_ctor then - rawset(obj,'super',function(obj,...) - call_ctor(base,obj,...) - end) - end - end - local res = c._init(obj,...) - rawset(obj,'super',nil) - return res -end - ---- initializes an __instance__ upon creation. --- @function class:_init --- @param ... parameters passed to the constructor --- @usage local Cat = class() --- function Cat:_init(name) --- --self:super(name) -- call the ancestor initializer if needed --- self.name = name --- end --- --- local pussycat = Cat("pussycat") --- print(pussycat.name) --> pussycat - ---- checks whether an __instance__ is derived from some class. --- Works the other way around as `class_of`. --- @function instance:is_a --- @param some_class class to check against --- @return `true` if `instance` is derived from `some_class` --- @usage local pussycat = Lion() -- assuming Lion derives from Cat --- if pussycat:is_a(Cat) then --- -- it's true --- end -local function is_a(self,klass) - local m = getmetatable(self) - if not m then return false end --*can't be an object! - while m do - if m == klass then return true end - m = rawget(m,'_base') - end - return false -end - ---- checks whether an __instance__ is derived from some class. --- Works the other way around as `is_a`. --- @function some_class:class_of --- @param some_instance instance to check against --- @return `true` if `some_instance` is derived from `some_class` --- @usage local pussycat = Lion() -- assuming Lion derives from Cat --- if Cat:class_of(pussycat) then --- -- it's true --- end -local function class_of(klass,obj) - if type(klass) ~= 'table' or not rawget(klass,'is_a') then return false end - return klass.is_a(obj,klass) -end - ---- cast an object to another class. --- It is not clever (or safe!) so use carefully. --- @param some_instance the object to be changed --- @function some_class:cast -local function cast (klass, obj) - return setmetatable(obj,klass) -end - - -local function _class_tostring (obj) - local mt = obj._class - local name = rawget(mt,'_name') - setmetatable(obj,nil) - local str = tostring(obj) - setmetatable(obj,mt) - if name then str = name ..str:gsub('table','') end - return str -end - -local function tupdate(td,ts,dont_override) - for k,v in pairs(ts) do - if not dont_override or td[k] == nil then - td[k] = v - end - end -end - -local function _class(base,c_arg,c) - -- the class `c` will be the metatable for all its objects, - -- and they will look up their methods in it. - local mt = {} -- a metatable for the class to support __call and _handler - -- can define class by passing it a plain table of methods - local plain = type(base) == 'table' and not getmetatable(base) - if plain then - c = base - base = c._base - else - c = c or {} - end - - if type(base) == 'table' then - -- our new class is a shallow copy of the base class! - -- but be careful not to wipe out any methods we have been given at this point! - tupdate(c,base,plain) - c._base = base - -- inherit the 'not found' handler, if present - if rawget(c,'_handler') then mt.__index = c._handler end - elseif base ~= nil then - error("must derive from a table type",3) - end - - c.__index = c - setmetatable(c,mt) - if not plain then - c._init = nil - end - - if base and rawget(base,'_class_init') then - base._class_init(c,c_arg) - end - - -- expose a ctor which can be called by <classname>(<args>) - mt.__call = function(class_tbl,...) - local obj - if rawget(c,'_create') then obj = c._create(...) end - if not obj then obj = {} end - setmetatable(obj,c) - - if rawget(c,'_init') then -- explicit constructor - local res = call_ctor(c,obj,...) - if res then -- _if_ a ctor returns a value, it becomes the object... - obj = res - setmetatable(obj,c) - end - elseif base and rawget(base,'_init') then -- default constructor - -- make sure that any stuff from the base class is initialized! - call_ctor(base,obj,...) - end - - if base and rawget(base,'_post_init') then - base._post_init(obj) - end - - if not rawget(c,'__tostring') then - c.__tostring = _class_tostring - end - return obj - end - -- Call Class.catch to set a handler for methods/properties not found in the class! - c.catch = function(self, handler) - if type(self) == "function" then - -- called using . instead of : - handler = self - end - c._handler = handler - mt.__index = handler - end - c.is_a = is_a - c.class_of = class_of - c.cast = cast - c._class = c - - return c -end - ---- create a new class, derived from a given base class. --- Supporting two class creation syntaxes: --- either `Name = class(base)` or `class.Name(base)`. --- The first form returns the class directly and does not set its `_name`. --- The second form creates a variable `Name` in the current environment set --- to the class, and also sets `_name`. --- @function class --- @param base optional base class --- @param c_arg optional parameter to class constructor --- @param c optional table to be used as class -local class -class = setmetatable({},{ - __call = function(fun,...) - return _class(...) - end, - __index = function(tbl,key) - if key == 'class' then - io.stderr:write('require("pl.class").class is deprecated. Use require("pl.class")\n') - return class - end - compat = compat or require 'pl.compat' - local env = compat.getfenv(2) - return function(...) - local c = _class(...) - c._name = key - rawset(env,key,c) - return c - end - end -}) - -class.properties = class() - -function class.properties._class_init(klass) - klass.__index = function(t,key) - -- normal class lookup! - local v = klass[key] - if v then return v end - -- is it a getter? - v = rawget(klass,'get_'..key) - if v then - return v(t) - end - -- is it a field? - return rawget(t,'_'..key) - end - klass.__newindex = function (t,key,value) - -- if there's a setter, use that, otherwise directly set table - local p = 'set_'..key - local setter = klass[p] - if setter then - setter(t,value) - else - rawset(t,key,value) - end - end -end - - -return class - |