delegates.md

Delegates

Lambdas

Lambdas lower to Lua anonymous functions.

Func<int, int, bool> less = (a, b) => a < b;

local less = function(a, b)
    return (a < b)
end

Func<>

Func<T1, ..., TResult> and Action<T1, ...> are valid field, local, and parameter types. The delegate is stored as a Lua function value and called directly.

public Func<int, bool> Filter;

Filter = x => x > 0;
bool ok = Filter(5);

self.Filter = function(x)
    return (x > 0)
end
local ok = self.Filter(5)

Bound instance method groups passed to delegate parameters lower as receiver-capturing lambdas before emission. For example, _units.Add passed to an Action<unit> parameter lowers like u => _units.Add(u), then collection lowering emits the usual list helper call.

ExTriggerRegisterNewUnit(function(u)
    SF__.ListAdd__(self._units, u)
end)

Statement-form conditional delegate invocation is supported. SharpForge evaluates the receiver once, stores it in a temporary, and only invokes when that temporary is non-nil.

handler?.Invoke(value);

local delegate = handler
if (delegate ~= nil) then
    delegate(value)
end

Operator Overloads

Operator overloads (operator +, operator ==, etc.) lower to static functions named with a suffix. They are not called implicitly by the transpiler for built-in binary expressions; they must be called explicitly or the transpiler will use the operator directly.

Unsupported

Multi-cast delegates (+= for event subscription outside field-like events), delegate declarations, and event with custom add/remove accessors produce a transpiler error.