Str

These types are subclasses of built-in str type with some constraints on it.

InitHook

Type with special __init_hook__ method which is called on instantiation. It can be used to perform some additional checks on the value.

from valtypes.type.str import InitHook
from valtypes.error.parsing import Base as ParsingError


class Uppercase(InitHook):
    def __init_hook__(self) -> None:
        if not self.isupper():
            raise ParsingError(f"{self!r} is not uppercase")


Uppercase("FOO")  # passes
Uppercase("foo")  # raises ParsingError

MinimumLength

Type for representing a str that has a given minimum length. The minimum allowed length is stored in the __minimum_length__ attribute.

from valtypes.type.str import MinimumLength


class AtLeastTwoChars(MinimumLength):
    __minimum_length__ = 2


AtLeastTwoChars("foo")  # passes
AtLeastTwoChars("f")  # raises valtypes.error.parsing.type.sized.MinimumLength

MaximumLength

Type for representing a str that has a given maximum length. The maximum allowed length is stored in the __maximum_length__ attribute.

from valtypes.type.str import MaximumLength


class AtMostTwoChars(MaximumLength):
    __maximum_length__ = 2


AtMostTwoChars("foo")  # passes
AtMostTwoChars("fooo")  # raises valtypes.error.parsing.type.sized.MaximumLength

NonEmpty

Type for representing a non-empty str. It is a subclass of MinimumLength with __minimum_length__ set to 1.

from valtypes.type.str import NonEmpty

NonEmpty("foo")  # passes
NonEmpty()  # raises valtypes.error.parsing.type.sized.MinimumLength

Pattern

Type for representing a str that fully matches a given regular expression. The regular expression is stored in the __pattern__ attribute.

import re

from valtypes.type.str import Pattern


class Numeric(Pattern):
    __pattern__ = re.compile(r"\d+")


Numeric("123")  # passes
Numeric("foo")  # raises valtypes.error.parsing.type.str.Pattern