casacore
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#include <DataType.h>
Public Types | |
enum | DataType { TpBool , TpChar , TpUChar , TpShort , TpUShort , TpInt , TpUInt , TpFloat , TpDouble , TpComplex , TpDComplex , TpString , TpTable , TpArrayBool , TpArrayChar , TpArrayUChar , TpArrayShort , TpArrayUShort , TpArrayInt , TpArrayUInt , TpArrayFloat , TpArrayDouble , TpArrayComplex , TpArrayDComplex , TpArrayString , TpRecord , TpOther , TpQuantity , TpArrayQuantity , TpInt64 , TpArrayInt64 , TpNumberOfTypes } |
Public Member Functions | |
ostream & | operator<< (ostream &os, DataType type) |
Write a formated representation (e.g., Type=Bool) of the given data type. | |
template<typename T > | |
DataType | whatType () |
These (specialized) functions return the DataType that corresponds to the template type. | |
DataType | asScalar (DataType type) |
It is sometimes useful to discover what the corresponding scalar (or array) type is for a given array (or scalar) type. | |
DataType | asArray (DataType type) |
Bool | isScalar (DataType type) |
It is occasionally useful to discover whether or not a DataType represents an array or scalar value. | |
Bool | isArray (DataType type) |
Bool | isScalarFun (DataType type) |
Bool | isReal (DataType type) |
It is sometimes useful to discover if a DataType represents a real numeric value (i.e., can it be cast to a Double?) This returns True for both real scalar and array type. | |
Bool | isComplex (DataType type) |
Returns True for Complex or DComplex scalar or array types. | |
Bool | isNumeric (DataType type) |
Returns True if the type is either Real or Complex/DComplex. | |
Data types (primarily) in the table system
Public interface
DataType enumerates possible data types. While this enum is primarily used in the table system, some use of it is made elsewhere. Besides the enum itself, operator<<
is defined for DataType; it prints a DataType in the form DataType=Bool
.
Also, global functions are written which take a "const pointer to type" and return its DataType (TpOther if unknown). These functions can occasionally allow one to avoid a switch on type, and can be useful in constructing templated classes which are only valid for certain types.
Global functions are also provided which allow one to convert an array type to the equivalent scalar type and vice versa.
Warning: New data types should be added just before TpNumberOfTypes, and after all the existing enumerations, to avoid changing the number of an existing type which would cause misinterpretation of data types stored in existing files; Note also that if any new scalar and array types are added that this will break the exising isScalar, isArray, asScalar and asArray functions;
Tip: Data types long
and unsigned long
are not possible; The types Int
and uInt
are always 4 bytes, so long
is not needed and may only cause confusion;
The simplest uses of the DataType enumeration and functions are fairly obvious, for example:
A less obvious use is for "attaching" a templated object or function to a non-templated object in a safe way. For example:
So, this example provides a typesafe interface to values of only a small number of types (and it fairly gracefully allows additional types to be added; in particular the accessor class needs no modification). Techniques such as this are appropriate for situations where one needs to deal with many (but finite) numbers of types. For example, with FITS.
Enumeration of the possible data types for keywords and table columns.
Definition at line 139 of file DataType.h.
Definition at line 140 of file DataType.h.
It is sometimes useful to discover what the corresponding scalar (or array) type is for a given array (or scalar) type.
Calling these with TpOther, TpTable, and TpRecord results in an exception being thrown.
Returns True for Complex or DComplex scalar or array types.
Returns True if the type is either Real or Complex/DComplex.
It is sometimes useful to discover if a DataType represents a real numeric value (i.e., can it be cast to a Double?) This returns True for both real scalar and array type.
It is occasionally useful to discover whether or not a DataType represents an array or scalar value.
Note that TpTable, TpRecord, and TpOther are neither scalar nor array types.
ostream & casacore::DataType_global_functions_DataType::operator<< | ( | ostream & | os, |
DataType | type | ||
) |
Write a formated representation (e.g., Type=Bool) of the given data type.
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inline |
These (specialized) functions return the DataType that corresponds to the template type.
TpOther is returned for types that are not specialized, as is void.
Definition at line 167 of file DataType.h.
References TpOther.