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std
std.base64
std.boxer
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std.md5
std.mmfile
std.openrj
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std.boxer
This module is a set of types and functions for converting any object
(value or heap) into a generic box type, allowing the user to pass that
object around without knowing what's in the box, and then allowing him
to recover the value afterwards.
Example
// Convert the integer 45 into a box.
Box b = box(45);
// Recover the integer and cast it to real.
real r = unbox!(real)(b);
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That is the basic interface and will usually be all that you need to
understand. If it cannot unbox the object to the given type, it throws
UnboxException. As demonstrated, it uses implicit casts to behave in the
exact same way that static types behave. So for example, you can unbox
from int to real, but you cannot unbox from real to int: that would
require an explicit cast.
This therefore means that attempting to unbox an int as a string will
throw an error instead of formatting it. In general, you can call the
toString method on the box and receive a good result, depending upon
whether std.string.format accepts it.
Boxes can be compared to one another and they can be used as keys for
associative arrays.
There are also functions for converting to and from arrays of boxes.
Example
// Convert arguments into an array of boxes.
Box[] a = boxArray(1, 45.4, "foobar");
// Convert an array of boxes back into arguments.
TypeInfo[] arg_types;
void* arg_data;
boxArrayToArguments(a, arg_types, arg_data);
// Convert the arguments back into boxes using a
// different form of the function.
a = boxArray(arg_types, arg_data);
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One use of this is to support a variadic function more easily and
robustly; simply call "boxArray(_arguments, _argptr)", then
do whatever you need to do with the array.
- struct Box
- Box is a generic container for objects (both value and
heap), allowing the user to box them in a generic form and recover
them later.
- TypeInfo type
- Property for the type contained by the box. This is
initially null and cannot be assigned directly.
- void* data
- Property for the data pointer to the value of the box. This is
initially null and cannot be assigned directly.
- bit unboxable(TypeInfo type)
- Return whether the value could be unboxed as the given type without
throwing an error.
- char[] toString()
- Attempt to convert the boxed value into a string using
std.string.format; this will throw if that function cannot handle
it. If the box is uninitialized then this returns "".
- bit opEquals(Box other)
- Compare this box's value with another box. This implicitly casts
if the types are different, identical to the regular type system.
- float opCmp(Box other)
- Compare this box's value with another box. This implicitly casts
if the types are different, identical to the regular type system.
- uint toHash()
- Return the value's hash.
- Box box(...)
- Box the single argument passed to the function. If more or
fewer than one argument is passed, this will assert.
- Box box(TypeInfo type, void* data)
- Box the explicitly-defined object. type must not be null; data
must not be null if the type's size is greater than zero.
- Box[] boxArray(TypeInfo[] types, void* data)
Box[] boxArray(...)
- Convert a list of arguments into a list of boxes.
- void boxArrayToArguments(Box[] arguments, out TypeInfo[] types, out void* data)
- Convert a list of boxes into a list of arguments.
- bit unboxable!(T)(Box value)
- Return whether the value can be unboxed as the given type; if this
returns false, attempting to do so will throw UnboxException.
- T unbox!(T)(Box value)
- This template function converts a boxed value into the provided
type. To use it, instantiate the template with the desired result
type, and then call the function with the box to convert.
This will implicitly cast base types as necessary and in a way
consistent with static types - for example, it will cast a boxed byte
into int, but it won't cast a boxed float into short. If it cannot
cast, it throws UnboxException.
Example
Box b = box(4.5);
bit u = unboxable!(real)(b); // This is true.
real r = unbox!(real)(b);
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- class UnboxException : Error
- This class is thrown if unbox is unable to cast the value into the
desired result.
- this(Box object, TypeInfo outputType)
- Assign parameters and create the message in the
form "Could not unbox from type to ."
- box object
- This is the box that the user attempted to unbox.
- TypeInfo outputType
- This is the type that the user attempted to unbox the value as.
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