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# object

Forms the symbols available to all D programs. Includes Object, which is the root of the class `object` hierarchy. This module is implicitly imported.
License:
Boost License 1.0.
Authors:
Walter Bright, Sean Kelly

class `Object`;
  All D class objects inherit from `Object`.
  string `toString`();
    Convert Object to a human readable string.
  nothrow @trusted size_t `toHash`();
    Compute hash function for Object.
  int `opCmp`(Object `o`);
    Compare with another Object obj.
    Returns:

    this < obj | < 0
    this == obj | 0
    this > obj | > 0

  bool `opEquals`(Object `o`);
    Test whether this is equal to `o`. The default implementation only compares by identity (using the is operator). Generally, overrides for `opEquals` should attempt to compare objects by their contents.
  static Object `factory`(string `classname`);
    Create instance of class specified by the fully qualified name `classname`. The class must either have no constructors or have a default constructor.
    Returns:
    `null` if failed

    Example:

        module foo.bar;

        class C
        {
            this() { x = 10; }
            int x;
        }

        void main()
        {
            auto c = cast(C)Object.factory("foo.bar.C");
            assert(c !is null && c.x == 10);
        }

auto `opEquals`(const Object `lhs`, const Object `rhs`);
  Returns `true` if `lhs` and `rhs` are equal.
struct `Interface`;
  Information about an interface. When an object is accessed via an interface, an `Interface`* appears as the first entry in its vtbl.
  TypeInfo_Class `classinfo`;
    .`classinfo` for this interface (not for containing class)
  size_t `offset`;
    `offset` to Interface 'this' from Object 'this'
struct `OffsetTypeInfo`;
  Array of pairs giving the offset and type information for each member in an aggregate.
  size_t `offset`;
    Offset of member from start of object
  TypeInfo `ti`;
    TypeInfo for this member
abstract class `TypeInfo`;
  Runtime type information about a type. Can be retrieved for any type using a TypeidExpression.
  const nothrow @trusted size_t `getHash`(in void* `p`);
    Computes a hash of the instance of a type.
    Parameters:

    void* `p` | pointer to start of instance of the type

    Returns:
    the hash
    Bugs:
    fix https://issues.dlang.org/show_bug.cgi?id=12516 e.g. by changing this to a truly safe interface.
  const bool `equals`(in void* `p1`, in void* `p2`);
    Compares two instances for equality.
  const int `compare`(in void* `p1`, in void* `p2`);
    Compares two instances for <, ==, or >.
  const pure nothrow @nogc @property @safe size_t `tsize`();
    Returns size of the type.
  const void `swap`(void* `p1`, void* `p2`);
    Swaps two instances of the type.
  inout pure nothrow @nogc @property inout(TypeInfo) `next`();
    Get TypeInfo for '`next`' type, as defined by what kind of type this is, `null` if none.
  abstract const pure nothrow @nogc @safe const(void)[] `initializer`();
    Return default `initializer`. If the type should be initialized to all zeros, an array with a `null` ptr and a length equal to the type size will be returned. For static arrays, this returns the default `initializer` for a single element of the array, use tsize to get the correct size.
  const pure nothrow @nogc @property @safe uint `flags`();
    Get `flags` for type: 1 means GC should scan for pointers, 2 means arg of this type is passed in XMM register
  const const(OffsetTypeInfo)[] `offTi`();
    Get type information on the contents of the type; `null` if not available
  const void `destroy`(void* `p`);
    Run the destructor on the object and all its sub-objects
  const void `postblit`(void* `p`);
    Run the `postblit` on the object and all its sub-objects
  const pure nothrow @nogc @property @safe size_t `talign`();
    Return alignment of type
  const pure nothrow @nogc @property @safe immutable(void)* `rtInfo`();
    Return info used by the garbage collector to do precise collection.
class `TypeInfo_Class`: object.TypeInfo;
  Runtime type information about a class. Can be retrieved from an object instance by using the .classinfo property.
  byte[] `m_init`;
    class static initializer (init.length gives size in bytes of class)
  string `name`;
    class `name`
  void*[] `vtbl`;
    virtual function pointer table
  Interface[] `interfaces`;
    `interfaces` this class implements
  TypeInfo_Class `base`;
    `base` class
  static const(TypeInfo_Class) `find`(in char[] `classname`);
    Search all modules for TypeInfo_Class corresponding to `classname`.
    Returns:
    `null` if not found
  const Object `create`();
    Create instance of Object represented by 'this'.
class `Throwable`;
  The base class of all thrown objects.
  All thrown objects must inherit from `Throwable`. Class Exception, which derives from this class, represents the category of thrown objects that are safe to catch and handle. In principle, one should not catch `Throwable` objects that are not derived from Exception, as they represent unrecoverable runtime errors. Certain runtime guarantees may fail to hold when these errors are thrown, making it unsafe to continue execution after catching them.
  string `msg`;
    A message describing the error.
  string `file`;
  size_t `line`;
    The file name and `line` number of the D source code corresponding with where the error was thrown from.
  TraceInfo `info`;
    The stack trace of where the error happened. This is an opaque object that can either be converted to string, or iterated over with foreach to extract the items in the stack trace (as strings).
  Throwable `next`;
    A reference to the next error in the list. This is used when a new Throwable is thrown from inside a catch block. The originally caught Exception will be chained to the new Throwable via this field.
  string `toString`();
    Overrides Object.`toString` and returns the error message. Internally this forwards to the `toString` overload that takes a sink delegate.
  const void `toString`(scope void delegate(in char[]) `sink`);
    The Throwable hierarchy uses a `toString` overload that takes a sink delegate to avoid GC allocations, which cannot be performed in certain error situations. Override this `toString` method to customize the error message.
class `Exception`: object.Throwable;
  The base class of all errors that are safe to catch and handle.
  In principle, only thrown objects derived from this class are safe to catch inside a catch block. Thrown objects not derived from `Exception` represent runtime errors that should not be caught, as certain runtime guarantees may not hold, making it unsafe to continue program execution.
  pure nothrow @nogc @safe this(string `msg`, string `file` = __FILE__, size_t `line` = __LINE__, Throwable `next` = null);
    Creates a new instance of Exception. The `next` parameter is used internally and should always be `null` when passed by user code. This constructor does not automatically throw the newly-created Exception; the throw statement should be used for that purpose.
class `Error`: object.Throwable;
  The base class of all unrecoverable runtime errors.
  This represents the category of Throwable objects that are not safe to catch and handle. In principle, one should not catch `Error` objects, as they represent unrecoverable runtime errors. Certain runtime guarantees may fail to hold when these errors are thrown, making it unsafe to continue execution after catching them.
  pure nothrow @nogc @safe this(string `msg`, Throwable `next` = null);
    Creates a new instance of Error. The `next` parameter is used internally and should always be `null` when passed by user code. This constructor does not automatically throw the newly-created Error; the throw statement should be used for that purpose.
  Throwable `bypassedException`;
    The first Exception which was bypassed when this Error was thrown, or `null` if no Exceptions were pending.
void `destroy`(T)(T `obj`)
if (is(T == class));
  Destroys the given object and puts it in an invalid state. It's used to `destroy` an object so that any cleanup which its destructor or finalizer does is done and so that it no longer references any other objects. It does not initiate a GC cycle or free any GC memory.
pure nothrow @property @trusted size_t `capacity`(T)(T[] `arr`);
  (Property) Get the current `capacity` of a slice. The `capacity` is the size that the slice can grow to before the underlying array must be reallocated or extended.
  If an append must reallocate a slice with no possibility of extension, then 0 is returned. This happens when the slice references a static array, or if another slice references elements past the end of the current slice.

  Note: The `capacity` of a slice may be impacted by operations on other slices.

  Examples:

      //Static array slice: no capacity
      int[4] sarray = [1, 2, 3, 4];
      int[]  slice  = sarray[];
      assert(sarray.capacity == 0);
      //Appending to slice will reallocate to a new array
      slice ~= 5;
      assert(slice.capacity >= 5);

      //Dynamic array slices
      int[] a = [1, 2, 3, 4];
      int[] b = a[1 .. $];
      int[] c = a[1 .. $ - 1];
      debug(SENTINEL) {} else // non-zero capacity very much depends on the array and GC implementation
      {
          assert(a.capacity != 0);
          assert(a.capacity == b.capacity + 1); //both a and b share the same tail
      }
      assert(c.capacity == 0);              //an append to c must relocate c.

pure nothrow @trusted size_t `reserve`(T)(ref T[] `arr`, size_t `newcapacity`);
  Reserves capacity for a slice. The capacity is the size that the slice can grow to before the underlying array must be reallocated or extended.
  The return value is the new capacity of the array (which may be larger than the requested capacity).
  Examples:

      //Static array slice: no capacity. Reserve relocates.
      int[4] sarray = [1, 2, 3, 4];
      int[]  slice  = sarray[];
      auto u = slice.reserve(8);
      assert(u >= 8);
      assert(sarray.ptr !is slice.ptr);
      assert(slice.capacity == u);

      //Dynamic array slices
      int[] a = [1, 2, 3, 4];
      a.reserve(8); //prepare a for appending 4 more items
      auto p = a.ptr;
      u = a.capacity;
      a ~= [5, 6, 7, 8];
      assert(p == a.ptr);      //a should not have been reallocated
      assert(u == a.capacity); //a should not have been extended

nothrow ref inout(T[]) `assumeSafeAppend`(T)(auto ref inout(T[]) `arr`);
  Assume that it is safe to append to this array. Appends made to this array after calling this function may append in place, even if the array was a slice of a larger array to begin with.
  Use this only when it is certain there are no elements in use beyond the array in the memory block. If there are, those elements will be overwritten by appending to this array.
  Calling this function, and then using references to data located after the given array results in undefined behavior.
  Returns:
  The input is returned.
  Examples:

      int[] a = [1, 2, 3, 4];

      // Without assumeSafeAppend. Appending relocates.
      int[] b = a [0 .. 3];
      b ~= 5;
      assert(a.ptr != b.ptr);

      debug(SENTINEL) {} else
      {
          // With assumeSafeAppend. Appending overwrites.
          int[] c = a [0 .. 3];
          c.assumeSafeAppend() ~= 5;
          assert(a.ptr == c.ptr);
      }

bool `_ArrayEq`(T1, T2)(T1[] `a1`, T2[] `a2`);
  Helper function used to see if two containers of different types have the same contents in the same sequence.
size_t `hashOf`(T)(auto ref T `arg`, size_t `seed` = 0);
  Calculates the hash value of `arg` with `seed` initial value. Result may be non-equals with typeid(T).getHash(&`arg`) The `seed` value may be used for hash chaining:

      struct Test
      {
          int a;
          string b;
          MyObject c;

          size_t toHash() const @safe pure nothrow
          {
              size_t hash = a.hashOf();
              hash = b.hashOf(hash);
              size_t h1 = c.myMegaHash();
              hash = h1.hashOf(hash); //Mix two hash values
              return hash;
          }
      }

enum auto `RTInfo`(T);
  Create `RTInfo` for type T
@property auto `dup`(T)(T[] `a`)
if (!is(const(T) : T));
@property T[] `dup`(T)(const(T)[] `a`)
if (is(const(T) : T));
  Provide the .`dup` array property.
@property immutable(T)[] `idup`(T)(T[] `a`);
@property immutable(T)[] `idup`(T : void)(const(T)[] `a`);
  Provide the .`idup` array property.

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