Stack overflow

[Benalish]

May I ask why this code goes into stack overflow

local function SetWidgetScript(frame,method)
    if frame:IsShown() then
        for i = 1, #frame.buttons do
            frame.buttons[i]:HookScript("OnMouseDown", method)
        end
    else
        frame:SetScript(
            "OnShow", --when "OnShow" is fired, IsShown() become true
                SetWidgetScript(frame,method)
        )
    end
end

While it works fine by simply wrapping myfunc() inside the function environment after "OnShow"?

local function SetWidgetScript(frame,method)
    if frame:IsShown() then
        for i = 1, #frame.buttons do
            frame.buttons[i]:HookScript("OnMouseDown", method)
        end
    else
        frame:SetScript(
            "OnShow", --when "OnShow" is fired, IsShown() become true
            function()
                SetWidgetScript(frame,method)
            end
        )
    end
end