diff --git a/extra_result/readme.md b/extra_result/readme.md
index ef296dd..562050a 100644
--- a/extra_result/readme.md
+++ b/extra_result/readme.md
@@ -6,7 +6,7 @@
A result object is a container for the result of an operation, which can be either a
success or a failure, together with the output of the operation. The result pattern
-is a fundamental part of the Rust programming language.
+is a fundamental part of the Rust programming language in the form of the [Result enum][rust_result].
### Class Diagram
@@ -18,13 +18,51 @@ classDiagram
}
```
-## Running the code
+## Example
+
+The filereader example uses the Result pattern to handle common errors reading and
+parsing json files. It puts all file reading and parsing logic into a single
+function, which returns a Result object. The calling code can check the status without
+needing to understand the details of the error.
+
+In this case we have correct files, a missing file and a bad file. All can be handled with the same
+approach, in this case using the LBYL philosophy.
+
+### Running the code
```bash
-python filereader.py
+ python filereader.py
```
+## Discussion
+
+People often say that
+in Python you should use exceptions - "Easier to Ask Forgiveness than Permission" (EAFP)
+over guard clauses - "Look Before You Leap" (LBYL),
+but the **Result design pattern** - returning an object which explicitly
+states whether the operation succeeded is a useful alternative where error handling is required and
+can be compatible with both approaches.
+
+## Use in Python
+
+The asyncio [Future object][asyncio_future] can be seen as a result object - it
+represents the result of an asynchronous operation but rather than a success or failure it is either done or not done.
+Confusingly it contains a `.result` attribute which is the output of the operation,
+but is not the same as the Result object in the Result pattern.
+
+The [requests library][requests] is often cited as a quintessentially
+pythonic library - its [response object][response] (representing
+the [HTTP response][http_response]) is essentially a **Result** object.
+The [`raise_for_status()`][raise_for_status] method lets you easily use it with the EAFP philosophy.
+
+[rust_result]: https://doc.rust-lang.org/std/result/enum.Result.html
+
+[asyncio_future]: https://docs.python.org/3/library/asyncio-future.html#future-object
+
+[raise_for_status]: https://docs.python-requests.org/en/latest/api/#requests.Response.raise_for_status
+
+[requests]: https://docs.python-requests.org/en/latest/index.html
-People often say you should use exceptions - "Easier to Ask Forgiveness than Permission" over guard clauses - "Look Before You Leap" but what about the Result design pattern - returning an object which explicitly states whether the operation succeeded (as used in Rust)?
+[response]: https://docs.python-requests.org/en/latest/api/#requests.Response
-The requests library is often cited as a quintessentially pythonic library - the response object in requests (representing a HTTP response) is essentially a Result object. The raise_for_status() method lets you use it with the EAFP philosophy.
+[http_response]: https://developer.mozilla.org/en-US/docs/Web/API/Response
\ No newline at end of file
pFad - Phonifier reborn
Pfad - The Proxy pFad of © 2024 Garber Painting. All rights reserved.
Note: This service is not intended for secure transactions such as banking, social media, email, or purchasing. Use at your own risk. We assume no liability whatsoever for broken pages.
Alternative Proxies:
Alternative Proxy
pFad Proxy
pFad v3 Proxy
pFad v4 Proxy