How do I _really_ implement opApply?

November 30, 2022

Posted by WebFreak001

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WebFreak001

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it seems now when trying to cover scope semantics, @safe/@system and pure it already becomes quite unmanagable to implement opApply properly.

Right now this is my solution:

private static enum opApplyImpl = q{
   int result;
   foreach (string key, ref value; this.table) {
      result = dg(key, value);
      if (result) {
         break;
      }
   }
   return result;
};

public int opApply(scope int delegate(string,       ref       TOMLValue) @safe   dg)      @safe              { mixin(opApplyImpl); }
public int opApply(scope int delegate(string,       ref const TOMLValue) @safe   dg)      @safe              { mixin(opApplyImpl); }
public int opApply(scope int delegate(string, scope ref       TOMLValue) @safe   dg)      @safe              { mixin(opApplyImpl); }
public int opApply(scope int delegate(string, scope ref const TOMLValue) @safe   dg)      @safe              { mixin(opApplyImpl); }
public int opApply(scope int delegate(string,       ref const TOMLValue) @safe   dg)      @safe const        { mixin(opApplyImpl); }
public int opApply(scope int delegate(string, scope ref const TOMLValue) @safe   dg)      @safe const        { mixin(opApplyImpl); }
public int opApply(scope int delegate(string,       ref       TOMLValue) @safe   pure dg) @safe pure         { mixin(opApplyImpl); }
public int opApply(scope int delegate(string,       ref const TOMLValue) @safe   pure dg) @safe pure         { mixin(opApplyImpl); }
public int opApply(scope int delegate(string, scope ref       TOMLValue) @safe   pure dg) @safe pure         { mixin(opApplyImpl); }
public int opApply(scope int delegate(string, scope ref const TOMLValue) @safe   pure dg) @safe pure         { mixin(opApplyImpl); }
public int opApply(scope int delegate(string,       ref const TOMLValue) @safe   pure dg) @safe pure const   { mixin(opApplyImpl); }
public int opApply(scope int delegate(string, scope ref const TOMLValue) @safe   pure dg) @safe pure const   { mixin(opApplyImpl); }
public int opApply(scope int delegate(string,       ref       TOMLValue) @system dg)      @system            { mixin(opApplyImpl); }
public int opApply(scope int delegate(string,       ref const TOMLValue) @system dg)      @system            { mixin(opApplyImpl); }
public int opApply(scope int delegate(string, scope ref       TOMLValue) @system dg)      @system            { mixin(opApplyImpl); }
public int opApply(scope int delegate(string, scope ref const TOMLValue) @system dg)      @system            { mixin(opApplyImpl); }
public int opApply(scope int delegate(string,       ref const TOMLValue) @system dg)      @system const      { mixin(opApplyImpl); }
public int opApply(scope int delegate(string, scope ref const TOMLValue) @system dg)      @system const      { mixin(opApplyImpl); }
public int opApply(scope int delegate(string,       ref       TOMLValue) @system pure dg) @system pure       { mixin(opApplyImpl); }
public int opApply(scope int delegate(string,       ref const TOMLValue) @system pure dg) @system pure       { mixin(opApplyImpl); }
public int opApply(scope int delegate(string, scope ref       TOMLValue) @system pure dg) @system pure       { mixin(opApplyImpl); }
public int opApply(scope int delegate(string, scope ref const TOMLValue) @system pure dg) @system pure       { mixin(opApplyImpl); }
public int opApply(scope int delegate(string,       ref const TOMLValue) @system pure dg) @system pure const { mixin(opApplyImpl); }
public int opApply(scope int delegate(string, scope ref const TOMLValue) @system pure dg) @system pure const { mixin(opApplyImpl); }

Surely there is a better way to do this?!

Better formatted:

formatted code

(note: I don't want to use a template, this way of writing it has the advantage that the compiler checks all different code paths for errors, so the errors aren't delayed until someone actually tries to iterate over my data structure)

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