Choice type

class pyasn1.type.univ.Choice(componentType=None, tagSet=tagSet(), subtypeSpec=ConstraintsIntersection(), sizeSpec=ConstraintsIntersection())

Create Choice type.

Choice objects are mutable and duck-type Python dict objects.

Parameters:
  • componentType (NamedType) – Object holding named ASN.1 types allowed within this collection
  • tagSet (TagSet) – Object representing non-default ASN.1 tag(s)
  • subtypeSpec (ConstraintsIntersection) – Object representing non-default ASN.1 subtype constraint(s)
  • sizeSpec (ConstraintsIntersection) – Object representing collection size constraint

Note

The Choice type can only hold a single component at a time belonging to the list of allowed types.

clone(componentType=None, tagSet=tagSet(), subtypeSpec=ConstraintsIntersection())

Create a copy of a Choice type or object.

Any parameters to the clone() method will replace corresponding properties of the Choice object.

Parameters:
  • tagSet (TagSet) – Object representing non-default ASN.1 tag(s)
  • subtypeSpec (ConstraintsIntersection) – Object representing non-default ASN.1 subtype constraint(s)
  • sizeSpec (ConstraintsIntersection) – Object representing non-default ASN.1 size constraint(s)
Returns:

new instance of Choice type/value

subtype(componentType=None, implicitTag=Tag(), explicitTag=Tag(), subtypeSpec=ConstraintsIntersection())

Create a copy of a Choice type or object.

Any parameters to the subtype() method will be added to the corresponding properties of the Choice object.

Parameters:
  • tagSet (TagSet) – Object representing non-default ASN.1 tag(s)
  • subtypeSpec (ConstraintsIntersection) – Object representing non-default ASN.1 subtype constraint(s)
  • sizeSpec (ConstraintsIntersection) – Object representing non-default ASN.1 size constraint(s)
Returns:

new instance of Choice type/value

tagSet = TagSet((), )

Set (on class, not on instance) or return a TagSet object representing ASN.1 tag(s) associated with Choice type.

componentType = NamedTypes()

Default collection of ASN.1 types of component (e.g. NamedType) object representing ASN.1 type allowed within Choice type

subtypeSpec = ConstraintsIntersection()

Set (on class, not on instance) or return a ConstraintsIntersection object imposing constraints on Choice type initialization values.

sizeSpec = ConstraintsIntersection(ValueSizeConstraint(1, 1))

Default ConstraintsIntersection object imposing size constraint on Choice objects

getComponentByName(name)

Returns Choice type component by name.

Equivalent to Python dict subscription operation (e.g. []).

Parameters:name (str) – Choice type component name
Returns:PyAsn1Item – Instantiate Choice component type or return existing component value
getComponentByType(tagSet, innerFlag=False)

Returns Choice type component by ASN.1 tag.

Parameters:tagSet (TagSet) – Object representing ASN.1 tags to identify one of Choice object component
Returns:PyAsn1Item – a pyasn1 object
isSameTypeWith(other, matchTags=True, matchConstraints=True)

Examine Choice type for equality with other ASN.1 type.

ASN.1 tags (tag) and constraints (constraint) are examined when carrying out ASN.1 types comparison.

No Python inheritance relationship between PyASN1 objects is considered.

Parameters:other (a pyasn1 type object) – Class instance representing ASN.1 type.
Returns:boolTrue if other is Choice type, False otherwise.
isSuperTypeOf(other, matchTags=True, matchConstraints=True)

Examine Choice type for subtype relationship with other ASN.1 type.

ASN.1 tags (tag) and constraints (constraint) are examined when carrying out ASN.1 types comparison.

No Python inheritance relationship between PyASN1 objects is considered.

Parameters:other (a pyasn1 type object) – Class instance representing ASN.1 type.
Returns:boolTrue if other is a subtype of Choice type, False otherwise.
setComponentByName(name, value=NoValue(), verifyConstraints=True, matchTags=True, matchConstraints=True)

Assign Choice type component by name.

Equivalent to Python dict item assignment operation (e.g. []).

Parameters:
  • name (str) – Choice type component name
  • value (object or PyAsn1Item derivative) – A Python value to initialize Choice component with (if componentType is set) or ASN.1 value object to assign to Choice component.
  • verifyConstraints (bool) – If False, skip constraints validation
  • matchTags (bool) – If False, skip component tags matching
  • matchConstraints (bool) – If False, skip component constraints matching
Returns:

self

setComponentByType(tagSet, value=NoValue(), verifyConstraints=True, matchTags=True, matchConstraints=True, innerFlag=False)

Assign Choice type component by ASN.1 tag.

Parameters:
  • tagSet (TagSet) – Object representing ASN.1 tags to identify one of Choice object component
  • value (object or PyAsn1Item derivative) – A Python value to initialize Choice component with (if componentType is set) or ASN.1 value object to assign to Choice component.
  • verifyConstraints (bool) – If False, skip constraints validation
  • matchTags (bool) – If False, skip component tags matching
  • matchConstraints (bool) – If False, skip component constraints matching
  • innerFlag (bool) – If True, search for matching tagSet recursively.
Returns:

self

setComponentByPosition(idx, value=NoValue(), verifyConstraints=True, matchTags=True, matchConstraints=True)

Assign Choice type component by position.

Equivalent to Python sequence item assignment operation (e.g. []).

Parameters:
  • idx (int) – Component index (zero-based). Must either refer to existing component or to N+1 component. In the latter case a new component type gets instantiated (if componentType is set, or given ASN.1 object is taken otherwise) and appended to the Choice sequence.
  • value (object or PyAsn1Item derivative) – A Python value to initialize Choice component with (if componentType is set) or ASN.1 value object to assign to Choice component. Once a new value is set to idx component, previous value is dropped.
  • verifyConstraints (bool) – If False, skip constraints validation
  • matchTags (bool) – If False, skip component tags matching
  • matchConstraints (bool) – If False, skip component constraints matching
Returns:

self

effectiveTagSet

Return a TagSet object of the currently initialized component or self (if Choice is tagged).

tagMap

“Return a TagMap object mapping ASN.1 tags to ASN.1 objects contained within callee.

getComponent(innerFlag=0)

Return currently assigned component of the Choice object.

Returns:PyAsn1Item – a PyASN1 object
getName(innerFlag=False)

Return the name of currently assigned component of the Choice object.

Returns:str – Choice component name
isValue

Indicate if Choice component is set and represents ASN.1 type or ASN.1 value.

The PyASN1 type objects can only participate in types comparison and serve as a blueprint for serialization codecs to resolve ambiguous types.

The PyASN1 value objects can additionally participate in most of built-in Python operations.

Returns:boolTrue if Choice component is set and represent value and type, False if Choice component is not set or it represents just ASN.1 type.