suggestions on passing a json as a function input












0















I am planning to write a routine to achieve below functionality: According to the "method", and "before" and "after", compute the expense. Not sure if passing a json as an input of the function is a good practice? Does it mean the function is trying to achieve too much? When I assign a default value to "target", Pycharm gives warning "mutable object as default argument".



def assign_expense(target={'fly':{'before':'US', 'after':'JP'}, 'walk':{'before':'blockA', 'after':'blockB'})

  method, before, after = abstract_param_from_json(target)

  if method='fly':

      if before=='US', after=='JP':

          func_fly_US_JP



      elif before=='MXN', after=='CAD':

          func_fly_MX_CAD

  if method='walk':

      if before=='blockA', after=='blockB':

               func_A_to_B



      if before=='blockC', after=='blockZ':

               func_C_to_Z





python







share|improve this question


















  • 1





    You should be very careful about mutable default arguments. They don't necessarily behave the way you think they should (hence the warning from Pycharm).

    – Jonah Bishop
    Nov 27 '18 at 1:47


















0















I am planning to write a routine to achieve below functionality: According to the "method", and "before" and "after", compute the expense. Not sure if passing a json as an input of the function is a good practice? Does it mean the function is trying to achieve too much? When I assign a default value to "target", Pycharm gives warning "mutable object as default argument".



def assign_expense(target={'fly':{'before':'US', 'after':'JP'}, 'walk':{'before':'blockA', 'after':'blockB'})

  method, before, after = abstract_param_from_json(target)

  if method='fly':

      if before=='US', after=='JP':

          func_fly_US_JP



      elif before=='MXN', after=='CAD':

          func_fly_MX_CAD

  if method='walk':

      if before=='blockA', after=='blockB':

               func_A_to_B



      if before=='blockC', after=='blockZ':

               func_C_to_Z





python







share|improve this question


















  • 1





    You should be very careful about mutable default arguments. They don't necessarily behave the way you think they should (hence the warning from Pycharm).

    – Jonah Bishop
    Nov 27 '18 at 1:47
















0












0








0








I am planning to write a routine to achieve below functionality: According to the "method", and "before" and "after", compute the expense. Not sure if passing a json as an input of the function is a good practice? Does it mean the function is trying to achieve too much? When I assign a default value to "target", Pycharm gives warning "mutable object as default argument".



def assign_expense(target={'fly':{'before':'US', 'after':'JP'}, 'walk':{'before':'blockA', 'after':'blockB'})

  method, before, after = abstract_param_from_json(target)

  if method='fly':

      if before=='US', after=='JP':

          func_fly_US_JP



      elif before=='MXN', after=='CAD':

          func_fly_MX_CAD

  if method='walk':

      if before=='blockA', after=='blockB':

               func_A_to_B



      if before=='blockC', after=='blockZ':

               func_C_to_Z





python







share|improve this question














I am planning to write a routine to achieve below functionality: According to the "method", and "before" and "after", compute the expense. Not sure if passing a json as an input of the function is a good practice? Does it mean the function is trying to achieve too much? When I assign a default value to "target", Pycharm gives warning "mutable object as default argument".



def assign_expense(target={'fly':{'before':'US', 'after':'JP'}, 'walk':{'before':'blockA', 'after':'blockB'})

  method, before, after = abstract_param_from_json(target)

  if method='fly':

      if before=='US', after=='JP':

          func_fly_US_JP



      elif before=='MXN', after=='CAD':

          func_fly_MX_CAD

  if method='walk':

      if before=='blockA', after=='blockB':

               func_A_to_B



      if before=='blockC', after=='blockZ':

               func_C_to_Z





python




python






share|improve this question













share|improve this question











share|improve this question




share|improve this question










asked Nov 27 '18 at 1:40









LisaLisa

1,00511537




1,00511537








  • 1





    You should be very careful about mutable default arguments. They don't necessarily behave the way you think they should (hence the warning from Pycharm).

    – Jonah Bishop
    Nov 27 '18 at 1:47
















  • 1





    You should be very careful about mutable default arguments. They don't necessarily behave the way you think they should (hence the warning from Pycharm).

    – Jonah Bishop
    Nov 27 '18 at 1:47










1




1





You should be very careful about mutable default arguments. They don't necessarily behave the way you think they should (hence the warning from Pycharm).

– Jonah Bishop
Nov 27 '18 at 1:47







You should be very careful about mutable default arguments. They don't necessarily behave the way you think they should (hence the warning from Pycharm).

– Jonah Bishop
Nov 27 '18 at 1:47














1 Answer
1






active

oldest

votes


















2














Regarding your warning mutable object as default argument



Please refer the following



https://docs.quantifiedcode.com/python-anti-patterns/correctness/mutable_default_value_as_argument.html



"Least Astonishment" and the Mutable Default Argument



Mutable objects as default arguments behave like a static variable



And regarding passing JSON as function input, I don't think it is a bad practice by itself unless the function is doing many things on the JSON.



Ex: If you need to delete/process a particular set of keys in the JSON, you need to pass JSON to the function that does the job.






share|improve this answer























    Your Answer






    StackExchange.ifUsing("editor", function () {
    StackExchange.using("externalEditor", function () {
    StackExchange.using("snippets", function () {
    StackExchange.snippets.init();
    });
    });
    }, "code-snippets");

    StackExchange.ready(function() {
    var channelOptions = {
    tags: "".split(" "),
    id: "1"
    };
    initTagRenderer("".split(" "), "".split(" "), channelOptions);

    StackExchange.using("externalEditor", function() {
    // Have to fire editor after snippets, if snippets enabled
    if (StackExchange.settings.snippets.snippetsEnabled) {
    StackExchange.using("snippets", function() {
    createEditor();
    });
    }
    else {
    createEditor();
    }
    });

    function createEditor() {
    StackExchange.prepareEditor({
    heartbeatType: 'answer',
    autoActivateHeartbeat: false,
    convertImagesToLinks: true,
    noModals: true,
    showLowRepImageUploadWarning: true,
    reputationToPostImages: 10,
    bindNavPrevention: true,
    postfix: "",
    imageUploader: {
    brandingHtml: "Powered by u003ca class="icon-imgur-white" href="https://imgur.com/"u003eu003c/au003e",
    contentPolicyHtml: "User contributions licensed under u003ca href="https://creativecommons.org/licenses/by-sa/3.0/"u003ecc by-sa 3.0 with attribution requiredu003c/au003e u003ca href="https://stackoverflow.com/legal/content-policy"u003e(content policy)u003c/au003e",
    allowUrls: true
    },
    onDemand: true,
    discardSelector: ".discard-answer"
    ,immediatelyShowMarkdownHelp:true
    });


    }
    });














    draft saved

    draft discarded


















    StackExchange.ready(
    function () {
    StackExchange.openid.initPostLogin('.new-post-login', 'https%3a%2f%2fstackoverflow.com%2fquestions%2f53491561%2fsuggestions-on-passing-a-json-as-a-function-input%23new-answer', 'question_page');
    }
    );

    Post as a guest















    Required, but never shown

























    1 Answer
    1






    active

    oldest

    votes








    1 Answer
    1






    active

    oldest

    votes









    active

    oldest

    votes






    active

    oldest

    votes









    2














    Regarding your warning mutable object as default argument



    Please refer the following



    https://docs.quantifiedcode.com/python-anti-patterns/correctness/mutable_default_value_as_argument.html



    "Least Astonishment" and the Mutable Default Argument



    Mutable objects as default arguments behave like a static variable



    And regarding passing JSON as function input, I don't think it is a bad practice by itself unless the function is doing many things on the JSON.



    Ex: If you need to delete/process a particular set of keys in the JSON, you need to pass JSON to the function that does the job.






    share|improve this answer




























      2














      Regarding your warning mutable object as default argument



      Please refer the following



      https://docs.quantifiedcode.com/python-anti-patterns/correctness/mutable_default_value_as_argument.html



      "Least Astonishment" and the Mutable Default Argument



      Mutable objects as default arguments behave like a static variable



      And regarding passing JSON as function input, I don't think it is a bad practice by itself unless the function is doing many things on the JSON.



      Ex: If you need to delete/process a particular set of keys in the JSON, you need to pass JSON to the function that does the job.






      share|improve this answer


























        2












        2








        2







        Regarding your warning mutable object as default argument



        Please refer the following



        https://docs.quantifiedcode.com/python-anti-patterns/correctness/mutable_default_value_as_argument.html



        "Least Astonishment" and the Mutable Default Argument



        Mutable objects as default arguments behave like a static variable



        And regarding passing JSON as function input, I don't think it is a bad practice by itself unless the function is doing many things on the JSON.



        Ex: If you need to delete/process a particular set of keys in the JSON, you need to pass JSON to the function that does the job.






        share|improve this answer













        Regarding your warning mutable object as default argument



        Please refer the following



        https://docs.quantifiedcode.com/python-anti-patterns/correctness/mutable_default_value_as_argument.html



        "Least Astonishment" and the Mutable Default Argument



        Mutable objects as default arguments behave like a static variable



        And regarding passing JSON as function input, I don't think it is a bad practice by itself unless the function is doing many things on the JSON.



        Ex: If you need to delete/process a particular set of keys in the JSON, you need to pass JSON to the function that does the job.







        share|improve this answer












        share|improve this answer



        share|improve this answer










        answered Nov 27 '18 at 1:49









        KrishnaKrishna

        6021515




        6021515
































            draft saved

            draft discarded




















































            Thanks for contributing an answer to Stack Overflow!


            • Please be sure to answer the question. Provide details and share your research!

            But avoid …



            • Asking for help, clarification, or responding to other answers.

            • Making statements based on opinion; back them up with references or personal experience.


            To learn more, see our tips on writing great answers.




            draft saved


            draft discarded














            StackExchange.ready(
            function () {
            StackExchange.openid.initPostLogin('.new-post-login', 'https%3a%2f%2fstackoverflow.com%2fquestions%2f53491561%2fsuggestions-on-passing-a-json-as-a-function-input%23new-answer', 'question_page');
            }
            );

            Post as a guest















            Required, but never shown





















































            Required, but never shown














            Required, but never shown












            Required, but never shown







            Required, but never shown

































            Required, but never shown














            Required, but never shown












            Required, but never shown







            Required, but never shown







            -

            Popular posts from this blog

            Contact image not getting when fetch all contact list from iPhone by CNContact

            Image
            up vote 0 down vote favorite I know this question already asked but not getting solution. From this code I will get all the information from the contact but image not found when open vcf files on mac os, also not getting when share this file. I use this stackoverflow link here but It's not help full. var contacts = [CNContact]() let keys = [CNContactVCardSerialization.descriptorForRequiredKeys() ] as [Any] let request = CNContactFetchRequest(keysToFetch: keys as! [CNKeyDescriptor]) do { try self.contactStore.enumerateContacts(with: request) { (contact, stop) in // Array containing all unified contacts from everywhere contacts.append(contact) } } catch { print("unable to fetch contacts") } do { let data = try
            Read more

            count number of partitions of a set with n elements into k subsets

            Image
            up vote 6 down vote favorite 1 This program is for count number of partitions of a set with n elements into k subsets I am confusing here return k*countP(n-1, k) + countP(n-1, k-1); can some one explain what is happening here? why we are multiplying with k? NOTE->I know this is not the best way to calculate number of partitions that would be DP // A C++ program to count number of partitions // of a set with n elements into k subsets #include<iostream> using namespace std; // Returns count of different partitions of n // elements in k subsets int countP(int n, int k) { // Base cases if (n == 0 || k == 0 || k > n) return 0; if (k == 1 || k == n) return 1; // S(n+1, k) = k*S(n, k) + S(n, k-1) return k*countP(n-1, k) + countP(n-1, k-1); } // Driver program int ma
            Read more

            A CLEAN and SIMPLE way to add appendices to Table of Contents and bookmarks

            Image
            0 I found a lot of questions abount appendices and ToC. Many users want appendices to be grouped in an Appendix part, however some problems arise with ToC, hyperref, PDF viewer bookmarks, and so on. There are different solutions which require extra packages, command patching and other extra code, however none of them satisfies me. I almost found an easy way to accomplish a good result, where appendices are added to bookmarks in the right way and hyperref links point to the right page. However, the number of the "Appendix" part page is wrong (it's the number of appendix A). Is there any EASY way to fix that? This is a MWE: documentclass{book} usepackage[nottoc,notlot,notlof]{tocbibind} usepackage{hyperref} begin{document} frontmatter tableofcontents mainmatter part{First} chapter{
            Read more