是否有更简单的方法来修改Erlang中subsubsub记录字段中的值？

Question

所以，我已经有了一个记录定义一个相当深的层次：

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现在我有一个安吉拉卷，我想使一个新的这 就像它除了一个价值sububsubrecords的子集。 这是我一直在做的事情。

update_attitude(Ench0, NewState) 
    when is_record(Ench0, enchilada)-> 

    %% Pick the old one apart. 
    #enchilada{stamped_packet  = SP0} = Ench0, 
    #stamped_packet{packet = PK0} = SP0, 
    #packet{cat = Tag0} = PK0, 

    %% Build up the new one. 
    Tude1 = Tude0#cat{attitude = NewState}, 
    PK1 = PK0#packet{cat = Tude1}, 
    SP1 = SP0#stamped_packet{packet = PK1}, 

    %% Thank God that's over. 
    Ench0#enchilada{stamped_packet = SP1}. 

只是思考这个是痛苦的。有没有更好的办法？

Answer 1

由于希内克建议，你可以在的Elid临时变量做：

update_attitude(E = #enchilada{stamped_packet = (P = #packet{cat=C})}, 
       NewAttitude) -> 
    E#enchilada{stamped_packet = P#packet{cat = C#cat{attitude=NewAttitude}}}. 

Yariv Sadan很沮丧与同样的问题，写Recless，a type inferring parse transform for records这样可以让你写：

-compile({parse_transform, recless}). 

update_attitude(Enchilada = #enchilada{}, Attitude) -> 
    Enchilada.stamped_packet.packet.cat.attitude = Attitude. 

Answer 2

试试这个：

update_attitude(E = #enchilada{ 
    stamped_packet = (SP = #stamped_packet{ 
     packet = (P = #packet{ 
     cat = C 
    })})}, NewState) -> 
    E#enchilada{ 
     stamped_packet = SP#stamped_packet{ 
     packet = P#packet{ 
      cat = C#cat{ 
      attitude = NewState 
    }}}}. 

反正，结构是不是二郎神的最有力的组成部分。