Skip to content

Result

Result type implementation inspired by Rust's Result enum.

result

Result type implementation inspired by Rust's Result enum.

ResultAccessError

Bases: Error

Exception raised when trying to access value or err from an inappropriate Result variant.

Source code in src/forging_blocks/foundation/result.py 
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
class ResultAccessError(Error):
    """Exception raised when trying to access value or err from an inappropriate Result variant."""

    def __init__(self, message: ErrorMessage | None = None) -> None:
        if message is None:
            message = ErrorMessage("Invalid access on Result type.")
        self._error_message = message
        super().__init__(message)

    def __str__(self) -> str:
        """Readable string representation."""
        return self._error_message.value

    @property
    def message(self) -> ErrorMessage:
        """Return the stored message as a string."""
        return self._error_message

    @classmethod
    def cannot_access_value(cls) -> ResultAccessError:
        """Create an error for accessing value from an Err Result."""
        return cls(ErrorMessage("Cannot access value from an Err Result."))

    @classmethod
    def cannot_access_error(cls) -> ResultAccessError:
        """Create an error for accessing error from an Ok Result."""
        return cls(ErrorMessage("Cannot access error from an Ok Result."))

message: ErrorMessage property

Return the stored message as a string.

__str__() -> str

Readable string representation.

Source code in src/forging_blocks/foundation/result.py 
23
24
25
def __str__(self) -> str:
    """Readable string representation."""
    return self._error_message.value

cannot_access_value() -> ResultAccessError classmethod

Create an error for accessing value from an Err Result.

Source code in src/forging_blocks/foundation/result.py 
32
33
34
35
@classmethod
def cannot_access_value(cls) -> ResultAccessError:
    """Create an error for accessing value from an Err Result."""
    return cls(ErrorMessage("Cannot access value from an Err Result."))

cannot_access_error() -> ResultAccessError classmethod

Create an error for accessing error from an Ok Result.

Source code in src/forging_blocks/foundation/result.py 
37
38
39
40
@classmethod
def cannot_access_error(cls) -> ResultAccessError:
    """Create an error for accessing error from an Ok Result."""
    return cls(ErrorMessage("Cannot access error from an Ok Result."))

Result

Bases: Generic[ResultType, ErrorType], Protocol

A type that represents either a success (Ok) or an error (Err).

Source code in src/forging_blocks/foundation/result.py 
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
class Result(Generic[ResultType, ErrorType], Protocol):
    """A type that represents either a success (Ok) or an error (Err)."""

    @property
    def is_ok(self) -> bool:
        """Guard method to check if that Result is an ok."""
        ...

    @property
    def is_err(self) -> bool:
        """Guard method to check if that Result is an err."""
        ...

    @property
    def value(self) -> ResultType | None:
        """Method to return the actual value. May raise an error if Result is an Err."""
        ...

    @property
    def error(self) -> ErrorType | None:
        """Method to return the actual error. May raise an error if Result is an Ok."""
        ...

is_ok: bool property

Guard method to check if that Result is an ok.

is_err: bool property

Guard method to check if that Result is an err.

value: ResultType | None property

Method to return the actual value. May raise an error if Result is an Err.

error: ErrorType | None property

Method to return the actual error. May raise an error if Result is an Ok.

Ok

Bases: Result[ResultType, ErrorType], Generic[ResultType, ErrorType]

Represents a successful result.

Source code in src/forging_blocks/foundation/result.py 
 67
 68
 69
 70
 71
 72
 73
 74
 75
 76
 77
 78
 79
 80
 81
 82
 83
 84
 85
 86
 87
 88
 89
 90
 91
 92
 93
 94
 95
 96
 97
 98
 99
100
101
102
103
104
105
106
107
108
109
class Ok(Result[ResultType, ErrorType], Generic[ResultType, ErrorType]):
    """Represents a successful result."""

    __match_args__ = ("_value",)

    def __init__(self, value: ResultType) -> None:
        self._value = value

    def __str__(self) -> str:
        """Return a string representation of the Ok result."""
        return f"Ok({self._value})"

    def __repr__(self) -> str:
        """Return a string representation of the Ok result."""
        return f"Ok({self._value!r})"

    def __eq__(self, other: object) -> bool:
        """Check equality with another Ok result."""
        return isinstance(other, Ok) and self._value == other._value

    def __hash__(self) -> int:
        """Return the hash of the Ok result."""
        return hash(self._value)

    @property
    def is_err(self) -> bool:
        """Check if the result is an error."""
        return False

    @property
    def is_ok(self) -> bool:
        """Check if the result is ok."""
        return True

    @property
    def value(self) -> ResultType:
        """Get the successful value."""
        return self._value

    @property
    def error(self) -> None:
        """Attempting to get error from an Ok result raises an error."""
        raise ResultAccessError.cannot_access_error()

is_err: bool property

Check if the result is an error.

is_ok: bool property

Check if the result is ok.

value: ResultType property

Get the successful value.

error: None property

Attempting to get error from an Ok result raises an error.

__str__() -> str

Return a string representation of the Ok result.

Source code in src/forging_blocks/foundation/result.py 
75
76
77
def __str__(self) -> str:
    """Return a string representation of the Ok result."""
    return f"Ok({self._value})"

__repr__() -> str

Return a string representation of the Ok result.

Source code in src/forging_blocks/foundation/result.py 
79
80
81
def __repr__(self) -> str:
    """Return a string representation of the Ok result."""
    return f"Ok({self._value!r})"

__eq__(other: object) -> bool

Check equality with another Ok result.

Source code in src/forging_blocks/foundation/result.py 
83
84
85
def __eq__(self, other: object) -> bool:
    """Check equality with another Ok result."""
    return isinstance(other, Ok) and self._value == other._value

__hash__() -> int

Return the hash of the Ok result.

Source code in src/forging_blocks/foundation/result.py 
87
88
89
def __hash__(self) -> int:
    """Return the hash of the Ok result."""
    return hash(self._value)

Err

Bases: Result[ResultType, ErrorType], Generic[ResultType, ErrorType]

Represents an error result.

Source code in src/forging_blocks/foundation/result.py 
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
class Err(Result[ResultType, ErrorType], Generic[ResultType, ErrorType]):
    """Represents an error result."""

    __match_args__ = ("_error",)

    def __init__(self, error: ErrorType) -> None:
        self._error = error

    def __repr__(self) -> str:
        """Return a string representation of the Err result."""
        return f"Err({self._error!r})"

    def __str__(self) -> str:
        """Return a string representation of the Err result."""
        return f"Err({self._error})"

    def __eq__(self, other: object) -> bool:
        """Check equality with another Err result."""
        return isinstance(other, Err) and self._error == other._error

    def __hash__(self) -> int:
        """Return the hash of the Err result."""
        return hash(self._error)

    @property
    def is_err(self) -> bool:
        """Check if the result is an error."""
        return True

    @property
    def is_ok(self) -> bool:
        """Check if the result is ok."""
        return False

    @property
    def value(self) -> None:
        """Attempting to get value from an Err result raises an error."""
        raise ResultAccessError.cannot_access_value()

    @property
    def error(self) -> ErrorType:
        """Get the error value."""
        return self._error

is_err: bool property

Check if the result is an error.

is_ok: bool property

Check if the result is ok.

value: None property

Attempting to get value from an Err result raises an error.

error: ErrorType property

Get the error value.

__repr__() -> str

Return a string representation of the Err result.

Source code in src/forging_blocks/foundation/result.py 
120
121
122
def __repr__(self) -> str:
    """Return a string representation of the Err result."""
    return f"Err({self._error!r})"

__str__() -> str

Return a string representation of the Err result.

Source code in src/forging_blocks/foundation/result.py 
124
125
126
def __str__(self) -> str:
    """Return a string representation of the Err result."""
    return f"Err({self._error})"

__eq__(other: object) -> bool

Check equality with another Err result.

Source code in src/forging_blocks/foundation/result.py 
128
129
130
def __eq__(self, other: object) -> bool:
    """Check equality with another Err result."""
    return isinstance(other, Err) and self._error == other._error

__hash__() -> int

Return the hash of the Err result.

Source code in src/forging_blocks/foundation/result.py 
132
133
134
def __hash__(self) -> int:
    """Return the hash of the Err result."""
    return hash(self._error)