Namespace hdf5::attribute

Classes

Attribute

class Attribute

Public Functions

Attribute(ObjectHandle &&handle, const node::Link &parent_link)

constructor

Parameters

• handle – rvalue reference to the attributes handle

• parent_link – like to the parent object

Attribute() = default

default constructor

Uses default compiler implementation.

datatype::Datatype datatype() const

return the data type of the attribute

Returns a copy of the datatype used to create the attribute.

dataspace::Dataspace dataspace() const

return the dataspace of the attribute

Returns the dataspace used to create the attribute.

std::string name() const

return the name of the attribute

bool is_valid() const

check if object is valid

void close()

close the attribute

This method will close the attribute and leave it in an invalid state. A subsequent call to is_valid should return false. The parent link remains valid though.

inline operator hid_t() const

conversion operator to hid_t

const node::Link &parent_link() const noexcept

get the parent ndoe

Return a reference to the node to which the attribute is attached.

template<typename T>
void write(const T &data) const

write data to attribute

Write data to disk. This is the simplest form of writting datat to disk. Its only argument is a reference to the object holding the data which should be written.

Throws

std::runtime_error – in case of a failure

Template Parameters

T – data type to write to disk

Parameters

data – reference to the datas instance

void write(const char *data) const

write string literal to disk

This is used whenever a string literal must be written to disk.

attribute::Attribute a = dataset.attributes.create<std::string>("note");
a.write("a short text");

You should be aware that this currently only works if the string type used for the attribute is a variable length string.

Throws

std::runtime_error – in case of a failure

template<typename T>
inline void write(const std::initializer_list<T> &list) const

write from initializer list

This method is used if the data to write is provided via an initializer list.

Attribute a = dataset.attributes.create<int>("index_list",{4});
a.write({56,23,4,12});

Internaly this method stores the content of the list to an instance of std::vector<T> which is then written to the attribute.

Template Parameters

T – type of the list elements

Parameters

list – reference to the initializer list

template<typename T>
void write(const T &data, const datatype::Datatype &mem_type) const

write data to disk

Write data to disk however we can pass a custom memory type to this method. This is particularly useful in the case of string types where the HDF5 datatype cannot be determined uniquely from a C++ type.

String fixed_type = String::fixed(20);
Attribute a = dataset.attributes.create("note",fixed_type,Scalar());

//we have to pass the type here explicitely otherwise the library
//would take std::string as a variable length string and HDF5
//considers variable and fixed length strings as incompatible.
std::string data = "hello";
a.write(data,fixed_type);

Throws

std::runtime_error – in case of an error

Template Parameters

T – type of input data

Parameters

• data – refernce to input data

• mem_type – HDF5 memory type of the input data

AttributeManager

class AttributeManager

provides STL interface for attributes

The AttributeManager class provides an STL compliant interface to access attribute attached to a Node.

Public Functions

AttributeManager(node::Node &node)

constructor

Creates a new instance of AttributeManager which must be attached to a Node instance.

Throws

std::runtime_error – in case of a failure

Parameters

node – reference to the parent node of the manager

AttributeManager(const AttributeManager &manager) = default

copy constructor

Use the compiler provided default implementation here.

Attribute operator[](size_t index) const

get attribute by index

Attribute operator[](const std::string &name) const

get attribute by name

size_t size() const

get number of attributes

void remove(const std::string &name) const

remove attribute by name

void remove(size_t index) const

remove attribute by index

Throws

std::runtime_error – in case of a failure

Pre

index must be < size()

bool exists(const std::string &name) const

check existence

Returns true if an attribute of given name exists. Otherwise false is returned.

void rename(const std::string &old_name, const std::string &new_name) const

rename an attribute

Throws

std::runtime_error – in case of a failure

Parameters

• old_name – old name of the attribute

• new_name – new name of the attribute

Attribute create(const std::string &name, const datatype::Datatype &datatype, const dataspace::Dataspace &dataspace, const property::AttributeCreationList &acpl = property::AttributeCreationList()) const

create an attribute

This is the most generic method to create attributes. See the template method below for more simple construction.

template<typename T>
Attribute create(const std::string &name, const property::AttributeCreationList &acpl = property::AttributeCreationList()) const

create scalar attribute

Create a scalar attribute of given name. The datatype is determined from the templat parameter.

Throws

std::runtime_error – in case of an error

Template Parameters

T – element data type of the attribute

Parameters

• name – the name of the attribute

• acpl – attribute creation property list

Returns

instance of the newly created attribute

template<typename T>
Attribute create(const std::string &name, const Dimensions &shape, const property::AttributeCreationList &acpl = property::AttributeCreationList()) const

create a multidimensional attribute

Create a multidimensional attribute of given name and shape. The datatype is derived from the template parameter.

Throws

std::runtime_error – in case of a failure

Template Parameters

T – element data type

Parameters

• name – the name for the attribute

• shape – the number of elements along each dimension

• acpl – attribute creation property list

Returns

instance of the newly created attribute

template<typename T>
Attribute create_from(const std::string &name, const T &value)

create a new attribute of a given value

This is a convenience method to create a new attribute with a given value. Technically this is a create() including a subsequent call to write.

Node n = ....;
n.attributes.create_from("date","12-03-2017");

Throws

std::runtime_error – in case of a failure

Parameters

• name – the name of the attribute

• value – reference to the new value

Returns

new instance of Attribute

IteratorConfig &iterator_config() noexcept

get iterator configuration

Use this method to get a reference to the iterator configuration for the attributes of a node.

Returns

reference to iterator configuration

const node::Node &node() const noexcept

get parent node

Return a reference to the parent node of the manager instance.

AttributeIterator begin() const

get iterator to first attribute

AttributeIterator end() const

get iterator to last+1 attribute

AttributeIterator

class AttributeIterator : public hdf5::Iterator