如何修改erlang中的记录？

Question

我需要修改操作记录中的值{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不允许修改变量。有没有数据类型？

Answer 1

erlang不会让你修改变量是真的。但没有任何东西阻止你制作一个变量的修改副本。

鉴于您的记录：

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后的版本，像这样：

%% 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}]} 

这将完成你仿佛在问。