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  3. How about new syntactical sugar for exception checking?

How about new syntactical sugar for exception checking?

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  • C Chris Maunder

    We get a shiny new "?" operator that takes

    string result = null;
    if (field != null)
    {
    result = field.Value;
    }

    and converts this to

    string result = field?.Value

    So what about the case where we're handling a flaky API

    string result = null;
    try
    {
    result = DodgyApi.GetValue(); // may throw an exception
    }
    catch
    {
    result = null;
    }

    What would you suggest we do for that? What about a headasplode (*) operator

    string result = DodgyApi.GetValue*();

    where GetValue* will silently swallow the exception thrown by GetValue and return default. Or am I setting a new standard for lazy, shameful programming here this hot, lazy afternoon?

    cheers Chris Maunder

    Kornfeld Eliyahu PeterK Offline
    Kornfeld Eliyahu PeterK Offline
    Kornfeld Eliyahu Peter
    wrote on last edited by
    #10

    As an idea I despite code that swallows exception without trace... Also null sometimes your best friend (but not default), so why to eliminate!?

    Skipper: We'll fix it. Alex: Fix it? How you gonna fix this? Skipper: Grit, spit and a whole lotta duct tape.

    "It never ceases to amaze me that a spacecraft launched in 1977 can be fixed remotely from Earth." ― Brian Cox

    B 1 Reply Last reply
    0
    • Richard DeemingR Richard Deeming

      Seems like an awful idea to me - I want code that silently swallows exceptions to be a pain to write. However, you could always add the suggestion to the Roslyn GitHub repo[^] for discussion. It doesn't seem half as mad as some of the other suggestions on there! :)


      "These people looked deep within my soul and assigned me a number based on the order in which I joined." - Homer

      R Offline
      R Offline
      Ryan Peden
      wrote on last edited by
      #11

      In this case, though, it's not really silently swallowing the exception. If the headasplode operator guarantees returning null on exceptions, then in using the operator your're explicitly expressing what you'd like to do if an exception occurs. It's more like exception handling shorthand than exception ignoring. :)

      Richard DeemingR B 2 Replies Last reply
      0
      • R Ryan Peden

        In this case, though, it's not really silently swallowing the exception. If the headasplode operator guarantees returning null on exceptions, then in using the operator your're explicitly expressing what you'd like to do if an exception occurs. It's more like exception handling shorthand than exception ignoring. :)

        Richard DeemingR Offline
        Richard DeemingR Offline
        Richard Deeming
        wrote on last edited by
        #12

        But with that operator, you've got to look closely at every method call to see whether or not it ignores exceptions. With the try..catch block, it's obvious what's happening. Also, how often do you really need to ignore every possible exception? Isn't it more likely that you'd want to ignore specific exception classes, and let unexpected exceptions propagate?


        "These people looked deep within my soul and assigned me a number based on the order in which I joined." - Homer

        "These people looked deep within my soul and assigned me a number based on the order in which I joined" - Homer

        R 1 Reply Last reply
        0
        • Richard DeemingR Richard Deeming

          But with that operator, you've got to look closely at every method call to see whether or not it ignores exceptions. With the try..catch block, it's obvious what's happening. Also, how often do you really need to ignore every possible exception? Isn't it more likely that you'd want to ignore specific exception classes, and let unexpected exceptions propagate?


          "These people looked deep within my soul and assigned me a number based on the order in which I joined." - Homer

          R Offline
          R Offline
          Ryan Peden
          wrote on last edited by
          #13

          I agree that making things as obvious as possible is a good approach. How do you feel about the way Java handles this, where exceptions are part of the method signature, i.e. int addSomeNumbers throws Abc { }. And if you call a method that throws an exception, you have to either handle or rethrow (and add the throws clause to your method) if you want your code to compile. A lot of people seem to hate Java's checked exceptions, but if you're working on a big enough corporate code base, in which case there are probably at least a few lazy or marginally competent developers on the team, I can see the value in checked exceptions.

          Richard DeemingR 1 Reply Last reply
          0
          • R Ryan Peden

            I agree that making things as obvious as possible is a good approach. How do you feel about the way Java handles this, where exceptions are part of the method signature, i.e. int addSomeNumbers throws Abc { }. And if you call a method that throws an exception, you have to either handle or rethrow (and add the throws clause to your method) if you want your code to compile. A lot of people seem to hate Java's checked exceptions, but if you're working on a big enough corporate code base, in which case there are probably at least a few lazy or marginally competent developers on the team, I can see the value in checked exceptions.

            Richard DeemingR Offline
            Richard DeemingR Offline
            Richard Deeming
            wrote on last edited by
            #14

            I can see the value, if they're done right. The temptation for lazy devs to add throws Exception is probably too high, though.


            "These people looked deep within my soul and assigned me a number based on the order in which I joined." - Homer

            "These people looked deep within my soul and assigned me a number based on the order in which I joined" - Homer

            1 Reply Last reply
            0
            • Kornfeld Eliyahu PeterK Kornfeld Eliyahu Peter

              As an idea I despite code that swallows exception without trace... Also null sometimes your best friend (but not default), so why to eliminate!?

              Skipper: We'll fix it. Alex: Fix it? How you gonna fix this? Skipper: Grit, spit and a whole lotta duct tape.

              B Offline
              B Offline
              Brisingr Aerowing
              wrote on last edited by
              #15

              Kornfeld Eliyahu Peter wrote:

              I despite code

              Quick Nitpick: that should be 'I despise code'. Despite means 'without being affected by; in spite of.', where despise means 'feel contempt or a deep repugnance for.'

              What do you get when you cross a joke with a rhetorical question? The metaphorical solid rear-end expulsions have impacted the metaphorical motorized bladed rotating air movement mechanism. Do questions with multiple question marks annoy you???

              1 Reply Last reply
              0
              • C Chris Maunder

                We get a shiny new "?" operator that takes

                string result = null;
                if (field != null)
                {
                result = field.Value;
                }

                and converts this to

                string result = field?.Value

                So what about the case where we're handling a flaky API

                string result = null;
                try
                {
                result = DodgyApi.GetValue(); // may throw an exception
                }
                catch
                {
                result = null;
                }

                What would you suggest we do for that? What about a headasplode (*) operator

                string result = DodgyApi.GetValue*();

                where GetValue* will silently swallow the exception thrown by GetValue and return default. Or am I setting a new standard for lazy, shameful programming here this hot, lazy afternoon?

                cheers Chris Maunder

                J Offline
                J Offline
                Jorgen Andersson
                wrote on last edited by
                #16

                This is a test, right?

                Wrong is evil and must be defeated. - Jeff Ello

                1 Reply Last reply
                0
                • C Chris Maunder

                  We get a shiny new "?" operator that takes

                  string result = null;
                  if (field != null)
                  {
                  result = field.Value;
                  }

                  and converts this to

                  string result = field?.Value

                  So what about the case where we're handling a flaky API

                  string result = null;
                  try
                  {
                  result = DodgyApi.GetValue(); // may throw an exception
                  }
                  catch
                  {
                  result = null;
                  }

                  What would you suggest we do for that? What about a headasplode (*) operator

                  string result = DodgyApi.GetValue*();

                  where GetValue* will silently swallow the exception thrown by GetValue and return default. Or am I setting a new standard for lazy, shameful programming here this hot, lazy afternoon?

                  cheers Chris Maunder

                  F Offline
                  F Offline
                  Foothill
                  wrote on last edited by
                  #17

                  To those of who still use pointers (even in .Net), using (*) might be a little confusing but I have an idea. How about using a construct similar to the for loop

                  // similar to...
                  for (int i = 0; i < limit; ++i) { ... }

                  // you can have
                  NoThrow (var <out>; Func<T>; <result on throw>);

                  // so your example becomes
                  string result;
                  NoThrow (result; dodgyApi.GetValue(); "I.M.Foo.Bar");

                  if (Object.DividedByZero == true) { Universe.Implode(); } Meus ratio ex fortis machina. Simplicitatis de formae ac munus. -Foothill, 2016

                  C Richard DeemingR 2 Replies Last reply
                  0
                  • C Chris Maunder

                    We get a shiny new "?" operator that takes

                    string result = null;
                    if (field != null)
                    {
                    result = field.Value;
                    }

                    and converts this to

                    string result = field?.Value

                    So what about the case where we're handling a flaky API

                    string result = null;
                    try
                    {
                    result = DodgyApi.GetValue(); // may throw an exception
                    }
                    catch
                    {
                    result = null;
                    }

                    What would you suggest we do for that? What about a headasplode (*) operator

                    string result = DodgyApi.GetValue*();

                    where GetValue* will silently swallow the exception thrown by GetValue and return default. Or am I setting a new standard for lazy, shameful programming here this hot, lazy afternoon?

                    cheers Chris Maunder

                    J Offline
                    J Offline
                    Joe Woodbury
                    wrote on last edited by
                    #18

                    "new" doesn't mean what you think it does.

                    1 Reply Last reply
                    0
                    • F Foothill

                      To those of who still use pointers (even in .Net), using (*) might be a little confusing but I have an idea. How about using a construct similar to the for loop

                      // similar to...
                      for (int i = 0; i < limit; ++i) { ... }

                      // you can have
                      NoThrow (var <out>; Func<T>; <result on throw>);

                      // so your example becomes
                      string result;
                      NoThrow (result; dodgyApi.GetValue(); "I.M.Foo.Bar");

                      if (Object.DividedByZero == true) { Universe.Implode(); } Meus ratio ex fortis machina. Simplicitatis de formae ac munus. -Foothill, 2016

                      C Offline
                      C Offline
                      Chris Maunder
                      wrote on last edited by
                      #19

                      Too explicit. We need something that truly, deeply hides what's going on ;)

                      cheers Chris Maunder

                      F 1 Reply Last reply
                      0
                      • C Chris Maunder

                        Too explicit. We need something that truly, deeply hides what's going on ;)

                        cheers Chris Maunder

                        F Offline
                        F Offline
                        Foothill
                        wrote on last edited by
                        #20

                        If that's the end goal, just use a carrot (^) instead of equals. That way anyone the uses managed C++ is really hosed. :laugh:

                        string result ^ dodgyApi.GetValue();

                        if (Object.DividedByZero == true) { Universe.Implode(); } Meus ratio ex fortis machina. Simplicitatis de formae ac munus. -Foothill, 2016

                        1 Reply Last reply
                        0
                        • R Ryan Peden

                          In this case, though, it's not really silently swallowing the exception. If the headasplode operator guarantees returning null on exceptions, then in using the operator your're explicitly expressing what you'd like to do if an exception occurs. It's more like exception handling shorthand than exception ignoring. :)

                          B Offline
                          B Offline
                          BillWoodruff
                          wrote on last edited by
                          #21

                          using System;

                          namespace InMemoriamMaunder
                          {
                          public enum DodgyResult
                          {
                          ResultNull,
                          ResultNonNull,
                          ResultError
                          }

                          public static class Dodgy
                          {
                              public static DodgyResult RunDodgy(ref T param, Func dodgyFunc)
                              {
                                  try
                                  {
                                      param = dodgyFunc(param);
                          
                                      if (param == null)
                                      {
                                          return DodgyResult.ResultNull;
                                      }
                                      else
                                      {
                                          return DodgyResult.ResultOkay;
                                      }
                                  }
                                  catch (Exception)
                                  {
                                       return DodgyResult.ResultError;
                                  }
                              }
                          }
                          

                          }

                          Tests:

                          private string SomeFuncError(string astring)
                          {
                          astring = null;
                          return astring.ToString();
                          }

                          private string SomeFuncNull(string astring)
                          {
                          astring = null;
                          return astring;
                          }

                          private string SomeFuncOkay(string astring)
                          {
                          astring = astring + astring;
                          return astring;
                          }

                          string astring1 = "hello";
                          string astring2 = null;
                          string astring3 = "whatever";

                          DodgyResult dr1 = Dodgy.RunDodgy(ref astring1, SomeFuncOkay);
                          DodgyResult dr2 = Dodgy.RunDodgy(ref astring2, SomeFuncNull);
                          DodgyResult dr3 = Dodgy.RunDodgy(ref astring3, SomeFuncError);

                          Now, Chris, all you have left to do is boil this down to a single operator :)

                          «There is a spectrum, from "clearly desirable behaviour," to "possibly dodgy behavior that still makes some sense," to "clearly undesirable behavior." We try to make the latter into warnings or, better, errors. But stuff that is in the middle category you don’t want to restrict unless there is a clear way to work around it.» Eric Lippert, May 14, 2008

                          Richard DeemingR 1 Reply Last reply
                          0
                          • C Chris Maunder

                            We get a shiny new "?" operator that takes

                            string result = null;
                            if (field != null)
                            {
                            result = field.Value;
                            }

                            and converts this to

                            string result = field?.Value

                            So what about the case where we're handling a flaky API

                            string result = null;
                            try
                            {
                            result = DodgyApi.GetValue(); // may throw an exception
                            }
                            catch
                            {
                            result = null;
                            }

                            What would you suggest we do for that? What about a headasplode (*) operator

                            string result = DodgyApi.GetValue*();

                            where GetValue* will silently swallow the exception thrown by GetValue and return default. Or am I setting a new standard for lazy, shameful programming here this hot, lazy afternoon?

                            cheers Chris Maunder

                            P Offline
                            P Offline
                            PIEBALDconsult
                            wrote on last edited by
                            #22

                            Just something along the lines of a TryGetValue<T> Extension Method. :shrug:

                            B 1 Reply Last reply
                            0
                            • P PIEBALDconsult

                              Just something along the lines of a TryGetValue<T> Extension Method. :shrug:

                              B Offline
                              B Offline
                              BillWoodruff
                              wrote on last edited by
                              #23

                              You get my up-vote for the idea, but making the idea more general-purpose means, imho, not being able to use an Extension method with generics, since the 'this parameter of an Extension method cannot be declared 'ref, or 'out. How about this (based on the code example in my previous reply to this thread)

                              using System;

                              namespace InMemoriamMaunder
                              {
                              public enum DodgyResult
                              {
                              ResultNull,
                              ResultOkay,
                              ResultError
                              }

                              public static class DodgyUtilities
                              {
                                  public static DodgyResult TryGetValueFromDodgy<T1,T2>(T1 t1, ref T2 t2, Func<T1,T2> func)
                                  {
                                      try
                                      {
                                          t2 = func(t1);
                              
                                          if (t2 == null)
                                          {
                                              return DodgyResult.ResultNull;
                                          }
                                          else
                                          {
                                              return DodgyResult.ResultOkay;
                                          }
                                      }
                                      catch (Exception)
                                      {
                                          return DodgyResult.ResultError;
                                      }
                                  }
                              }
                              

                              }

                              «There is a spectrum, from "clearly desirable behaviour," to "possibly dodgy behavior that still makes some sense," to "clearly undesirable behavior." We try to make the latter into warnings or, better, errors. But stuff that is in the middle category you don’t want to restrict unless there is a clear way to work around it.» Eric Lippert, May 14, 2008

                              1 Reply Last reply
                              0
                              • realJSOPR realJSOP

                                On the "?" operator - I will strive NEVER to use that. On the head-asplode operator - Shouldn't that be

                                string result = DodgyApi.GetValue?*.();

                                And why aren't you working on my latest feature request?*.() And please don't say you simply haven't GOTTEN around to it yet.

                                ".45 ACP - because shooting twice is just silly" - JSOP, 2010
                                -----
                                You can never have too much ammo - unless you're swimming, or on fire. - JSOP, 2010
                                -----
                                When you pry the gun from my cold dead hands, be careful - the barrel will be very hot. - JSOP, 2013

                                Sander RosselS Offline
                                Sander RosselS Offline
                                Sander Rossel
                                wrote on last edited by
                                #24

                                John Simmons / outlaw programmer wrote:

                                On the "?" operator - I will strive NEVER to use that.

                                Why? :confused:

                                Read my (free) ebook Object-Oriented Programming in C# Succinctly. Visit my blog at Sander's bits - Writing the code you need. Or read my articles here on CodeProject.

                                Simplicity is prerequisite for reliability. — Edsger W. Dijkstra

                                Regards, Sander

                                realJSOPR 1 Reply Last reply
                                0
                                • C Chris Maunder

                                  We get a shiny new "?" operator that takes

                                  string result = null;
                                  if (field != null)
                                  {
                                  result = field.Value;
                                  }

                                  and converts this to

                                  string result = field?.Value

                                  So what about the case where we're handling a flaky API

                                  string result = null;
                                  try
                                  {
                                  result = DodgyApi.GetValue(); // may throw an exception
                                  }
                                  catch
                                  {
                                  result = null;
                                  }

                                  What would you suggest we do for that? What about a headasplode (*) operator

                                  string result = DodgyApi.GetValue*();

                                  where GetValue* will silently swallow the exception thrown by GetValue and return default. Or am I setting a new standard for lazy, shameful programming here this hot, lazy afternoon?

                                  cheers Chris Maunder

                                  R Offline
                                  R Offline
                                  Roger Wright
                                  wrote on last edited by
                                  #25

                                  No programming questions in the Lounge! ;P

                                  Chris Maunder wrote:

                                  Or am I setting a new standard for lazy, shameful programming here this hot, lazy afternoon?

                                  Surely you jest! It's only 117° today, but we're supposed to warm up for the weekend.

                                  Will Rogers never met me.

                                  1 Reply Last reply
                                  0
                                  • C Chris Maunder

                                    We get a shiny new "?" operator that takes

                                    string result = null;
                                    if (field != null)
                                    {
                                    result = field.Value;
                                    }

                                    and converts this to

                                    string result = field?.Value

                                    So what about the case where we're handling a flaky API

                                    string result = null;
                                    try
                                    {
                                    result = DodgyApi.GetValue(); // may throw an exception
                                    }
                                    catch
                                    {
                                    result = null;
                                    }

                                    What would you suggest we do for that? What about a headasplode (*) operator

                                    string result = DodgyApi.GetValue*();

                                    where GetValue* will silently swallow the exception thrown by GetValue and return default. Or am I setting a new standard for lazy, shameful programming here this hot, lazy afternoon?

                                    cheers Chris Maunder

                                    D Offline
                                    D Offline
                                    Duncan Edwards Jones
                                    wrote on last edited by
                                    #26

                                    how about setting that as default for the whole app... you could use a constant like #ON_ERROR_RESUME_NEXT = true; ;P

                                    1 Reply Last reply
                                    0
                                    • N Nish Nishant

                                      You could always write a helper method.

                                      string GetString(int x)
                                      {
                                      throw new NotImplementedException();
                                      }

                                      void Foo()
                                      {
                                      string s = NoEx.Run(() => GetString(100));
                                      Console.WriteLine(s == null);
                                      }

                                      class NoEx
                                      {
                                      public static T Run<T>(Func<T> method)
                                      {
                                      try
                                      {
                                      return method();
                                      }
                                      catch
                                      {
                                      return default(T);
                                      }
                                      }
                                      }

                                      Not as clean as syntactic sugar, but fairly close :-)

                                      Regards, Nish


                                      Website: www.voidnish.com Blog: voidnish.wordpress.com

                                      CPalliniC Offline
                                      CPalliniC Offline
                                      CPallini
                                      wrote on last edited by
                                      #27

                                      :thumbsup:

                                      In testa che avete, signor di Ceprano?

                                      1 Reply Last reply
                                      0
                                      • Sander RosselS Sander Rossel

                                        John Simmons / outlaw programmer wrote:

                                        On the "?" operator - I will strive NEVER to use that.

                                        Why? :confused:

                                        Read my (free) ebook Object-Oriented Programming in C# Succinctly. Visit my blog at Sander's bits - Writing the code you need. Or read my articles here on CodeProject.

                                        Simplicity is prerequisite for reliability. — Edsger W. Dijkstra

                                        Regards, Sander

                                        realJSOPR Offline
                                        realJSOPR Offline
                                        realJSOP
                                        wrote on last edited by
                                        #28

                                        Because it obfuscates the code, and because I'm not yet coding in the appropriate version of .Net.

                                        ".45 ACP - because shooting twice is just silly" - JSOP, 2010
                                        -----
                                        You can never have too much ammo - unless you're swimming, or on fire. - JSOP, 2010
                                        -----
                                        When you pry the gun from my cold dead hands, be careful - the barrel will be very hot. - JSOP, 2013

                                        1 Reply Last reply
                                        0
                                        • C Chris Maunder

                                          I totally forgot about that! How about:

                                          #pragma on error resume next

                                          // ... code you wouldn't let your worst enemey near

                                          Mwahaha

                                          cheers Chris Maunder

                                          G Offline
                                          G Offline
                                          Gary Wheeler
                                          wrote on last edited by
                                          #29

                                          Who are you, and what have you done with that nice, wholesome Mr. Maunder?

                                          Software Zen: delete this;

                                          1 Reply Last reply
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