如何修改erlang中的記錄？

Question

我需要修改操作記錄中的值{place}和{other_place}。

#op{ 
    action = [walk, from, {place}, to, {other_place}], 
    preconds = [[at, {place}, me], [on, floor, me], 
       [other_place, {place}, {other_place}]], 
    add_list = [[at, {other_place}, me]], 
    del_list = [[at, {place}, me]] 
} 

但是erlang不允許修改變量。有沒有數據類型？

Answer 1

erlang不會讓你修改變量是真的。但沒有任何東西阻止你製作一個變量的修改副本。

鑑於您的記錄：

Rec = #op{ 
    action = [walk, from, {place}, to, {other_place}], 
    preconds = [[at, {place}, me], [on, floor, me], 
       [other_place, {place}, {other_place}]], 
    add_list = [[at, {other_place}, me]], 
    del_list = [[at, {place}, me]] 
} 

可以有效地得到修改後的版本，像這樣：

%% replaces the action field in Rec2 but everything else is the same as Rec. 
Rec2 = Rec#op{action = [walk, from, {new_place}, to, {new_other_place}]} 

這將完成你彷彿在問。