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DynamicAny conversion limits

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This commit is contained in:
Aleksandar Fabijanic
2007-04-25 01:11:49 +00:00
parent 109a6f47bd
commit f29f7cda53
4 changed files with 394 additions and 105 deletions
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31
Foundation/include/Poco/DynamicAny.h
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@@ -49,15 +49,30 @@ namespace Poco {
class Foundation_API DynamicAny
/// A DynamicAny allows to store data of different types and to convert between these types transparently.
/// It's the reponsibility of the programmer to ensure that conversions are meaningful.
/// For example: it is possible to convert between string and character. An empty string gets converted to
/// the char '\0', a non-empty string gets truncated to the very first character. Numeric values are truncated,
/// no overflow/underflow errors are checked. A string value "false" can be converted to a boolean value false,
/// any other string not "false" (not case sensitive) or "0" to true (e.g: "hi" -> true).
/// DynamicAny allows to store data of different types and to convert between these types transparently.
/// DynamicAny puts forth the best effort to provide intuitive and reasonable conversion semantics and prevent
/// unexpected data loss, particularly when performing narrowing or signedness conversions of numeric data types.
///
/// A DynamicAny can be created from a value of any type for which a
/// specialization of DynamicAnyHolderImpl is available.
/// Loss of signedness is not allowed for numeric values. This means that if an attempt is made to convert
/// the internal value which is a negative signed integer to an unsigned integer type storage, a RangeException is thrown.
/// Overflow is not allowed, so if the internal value is a larger number than the target numeric type size can accomodate,
/// a RangeException is thrown.
///
/// Precision loss, such as in conversion from floating-point types to integers or from double to float on platforms
/// where they differ in size (provided internal actual value fits in float min/max range), is allowed.
///
/// String truncation is allowed - it is possible to convert between string and character when string length is
/// greater than 1. An empty string gets converted to the char '\0', a non-empty string is truncated to the first character.
///
/// Bolean conversion are performed as follows:
///
/// A string value "false" (not case sensitive) or "0" can be converted to a boolean value false, any other string
/// not being false by the above criteria evaluates to true (e.g: "hi" -> true).
/// Integer 0 values are false, everything else is true.
/// Floating point values equal to the minimal FP representation on a given platform are false, everything else is true.
///
/// A DynamicAny can be created from and converted to a value of any type for which a specialization of
/// DynamicAnyHolderImpl is available. For supported types, see DynamicAnyHolder documentation.
{
public:
DynamicAny();