VisibleString type

class pyasn1.type.char.VisibleString(value=NoValue(), tagSet=TagSet(), subtypeSpec=ConstraintsIntersection(), encoding='us-ascii')

Creates VisibleString schema or value object.

VisibleString objects are immutable and duck-type Python 2 unicode or Python 3 str. When used in octet-stream context, VisibleString type assumes “us-ascii” encoding.

Keyword Arguments:
 
  • value (unicode, str, bytes or VisibleString object) – unicode object (Python 2) or string (Python 3), alternatively string (Python 2) or bytes (Python 3) representing octet-stream of serialised unicode string (note encoding parameter) or VisibleString class instance.
  • tagSet (TagSet) – Object representing non-default ASN.1 tag(s)
  • subtypeSpec (ConstraintsIntersection) – Object representing non-default ASN.1 subtype constraint(s)
  • encoding (str) – Unicode codec ID to encode/decode unicode (Python 2) or str (Python 3) the payload when VisibleString object is used in octet-stream context.
Raises:

PyAsn1Error – On constraint violation or bad initializer.

Note

The VisibleString type models a character string that can hold any “graphical” characters mixed with control ones to select particular alphabet.

clone(value=NoValue(), tagSet=TagSet(), subtypeSpec=ConstraintsIntersection(), encoding='us-ascii')

Create a modified version of VisibleString schema or value object.

The clone() method accepts the same set arguments as VisibleString class takes on instantiation except that all arguments of the clone() method are optional.

Whatever arguments are supplied, they are used to create a copy of self taking precedence over the ones used to instantiate self.

Note

Due to the immutable nature of the VisibleString object, if no arguments are supplied, no new VisibleString object will be created and self will be returned instead.

subtype(value=NoValue(), implicitTag=Tag(), explicitTag=Tag(), subtypeSpec=ConstraintsIntersection(), encoding='us-ascii')

Create a specialization of VisibleString schema or value object.

The subtype relationship between ASN.1 types has no correlation with subtype relationship between Python types. ASN.1 type is mainly identified by its tag(s) (TagSet) and value range constraints (ConstraintsIntersection). These ASN.1 type properties are implemented as VisibleString attributes.

The subtype() method accepts the same set arguments as VisibleString class takes on instantiation except that all parameters of the subtype() method are optional.

With the exception of the arguments described below, the rest of supplied arguments they are used to create a copy of self taking precedence over the ones used to instantiate self.

The following arguments to subtype() create a ASN.1 subtype out of VisibleString type:

Other Parameters:
 
  • implicitTag (Tag) – Implicitly apply given ASN.1 tag object to self’s TagSet, then use the result as new object’s ASN.1 tag(s).
  • explicitTag (Tag) – Explicitly apply given ASN.1 tag object to self’s TagSet, then use the result as new object’s ASN.1 tag(s).
  • subtypeSpec (ConstraintsIntersection) – Add ASN.1 constraints object to one of the self’s, then use the result as new object’s ASN.1 constraints.
Returns:

new instance of VisibleString schema or value object

Note

Due to the immutable nature of the VisibleString object, if no arguments are supplied, no new VisibleString object will be created and self will be returned instead.

tagSet = <TagSet object at 0x1051267b8 tags 0:0:26>

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

effectiveTagSet

For VisibleString type is equivalent to tagSet

isSameTypeWith(other, matchTags=True, matchConstraints=True)

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

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

Python class inheritance relationship is NOT considered.

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

Examine VisibleString 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.

Python class inheritance relationship is NOT considered.

Parameters:other (a pyasn1 type object) – Class instance representing ASN.1 type.
Returns:boolTrue if other is a subtype of VisibleString type, False otherwise.
isValue

Indicate that VisibleString object represents ASN.1 value.

If isValue is False then this object represents just ASN.1 schema.

If isValue is True then, in addition to its ASN.1 schema features, this object can also be used like a Python built-in object (e.g. int, str, dict etc.).

Returns:boolFalse if object represents just ASN.1 schema. True if object represents ASN.1 schema and can be used as a normal value.

Note

There is an important distinction between PyASN1 schema and value objects. The PyASN1 schema objects can only participate in ASN.1 schema-related operations (e.g. defining or testing the structure of the data). Most obvious uses of ASN.1 schema is to guide serialisation codecs whilst encoding/decoding serialised ASN.1 contents.

The PyASN1 value objects can additionally participate in many operations involving regular Python objects (e.g. arithmetic, comprehension etc).

tagMap

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