Add errors concept #686

meatball133 · 2024-08-10T22:22:15Z

No description provided.

ryanplusplus · 2024-08-11T11:13:04Z

concepts/errors/.meta/config.json

@@ -0,0 +1,5 @@
+{
+  "blurb": "Crystal has modules which can be used for namespacing and organizing code. It can also be used to create mixins and to extend classes.",


This looks like a copy paste error

ryanplusplus · 2024-08-11T11:14:15Z

concepts/errors/about.md

+raise "This is an error"
+```
+
+There are several built-in exceptions in Crystal, like `ArgumentError`, `IndexError`, `KeyError`, `IOError`, `SystemCallError`, `TypeError`, `ZeroDivisionError` and many more, these require you to pass a message to the exception.


Suggested change

There are several built-in exceptions in Crystal, like `ArgumentError`, `IndexError`, `KeyError`, `IOError`, `SystemCallError`, `TypeError`, `ZeroDivisionError` and many more, these require you to pass a message to the exception.

There are several built-in exceptions in Crystal, like `ArgumentError`, `IndexError`, `KeyError`, `IOError`, `SystemCallError`, `TypeError`, `ZeroDivisionError` and many more.

These require you to pass a message to the exception.

ryanplusplus · 2024-08-11T11:14:38Z

concepts/errors/about.md

+raise ArgumentError.new("This is an argument error")
+```
+
+## Handle exceptions


Suggested change

## Handle exceptions

## Handling exceptions

ryanplusplus · 2024-08-11T11:14:58Z

concepts/errors/about.md

+We wouldn't want our program to crash when an exception is raised.
+
+Therefore, when we know a piece of code is error prone, we can wrap it in a `begin` block and rescue the exception with a `rescue` block.


Suggested change

We wouldn't want our program to crash when an exception is raised.

Therefore, when we know a piece of code is error prone, we can wrap it in a `begin` block and rescue the exception with a `rescue` block.

We wouldn't want our program to crash when an exception is raised.

Therefore, when we know a piece of code is error prone, we can wrap it in a `begin` block and rescue the exception with a `rescue` block.

ryanplusplus · 2024-08-11T11:17:11Z

concepts/errors/about.md

+
+## Method convention
+
+If you have checked, specific methods have two versions, one with `!` and the other without.


Suggested change

If you have checked, specific methods have two versions, one with `!` and the other without.

Some methods have two versions, one with `!` and the other without.

ryanplusplus · 2024-08-11T11:23:01Z

exercises/concept/the-farm/.docs/hints.md

+## 2. Check the number of cows
+
+- `ValidateInputAndDivideFood` has the same function signature as `DivideFood`.
+- Since you want to return early in case of an error in Go, you first check whether the number of cows is less or equal than 0 with an if-statement.


Suggested change

- Since you want to return early in case of an error in Go, you first check whether the number of cows is less or equal than 0 with an if-statement.

- Since you want to return early in case of an error, you first check whether the number of cows is less or equal than 0 with an if-statement.

ryanplusplus · 2024-08-11T11:25:22Z

exercises/concept/the-farm/.docs/instructions.md

+Luckily, you don't need to work out all the formulas for calculating fodder amounts yourself.
+You use some mysterious external library that you found on the internet.
+It is supposed to result in the happiest cows.
+The library exposes a class that fulfils the following interface.


Suggested change

The library exposes a class that fulfils the following interface.

The library exposes a class that fulfills the following interface.

"Fulfil" is used in British English and "fulfill" is used in American English.

ryanplusplus · 2024-08-11T11:26:53Z

exercises/concept/the-farm/.docs/instructions.md

+
+## 3. Improve the error handling
+
+Checking the number of cows before passing it along was a good move but you are not quite happy with the unspecific error message.


Suggested change

Checking the number of cows before passing it along was a good move but you are not quite happy with the unspecific error message.

Checking the number of cows before passing it along was a good move but you are not quite happy with the vague error message.

ryanplusplus · 2024-08-11T11:27:18Z

exercises/concept/the-farm/.docs/instructions.md

+Checking the number of cows before passing it along was a good move but you are not quite happy with the unspecific error message.
+You decide to do better by creating a custom error class called `InvalidCowsError`.
+
+The custom error should hold the number of cows (`Int32`) and a custom message (`String`) and the `Expection` method should serialize the data in the following format:


Suggested change

The custom error should hold the number of cows (`Int32`) and a custom message (`String`) and the `Expection` method should serialize the data in the following format:

The custom error should hold the number of cows (`Int32`) and a custom message (`String`), and the `Expection` method should serialize the data in the following format:

ryanplusplus · 2024-08-11T11:30:08Z

concepts/errors/about.md

+Some methods raise an exception by default but also have a version ending with `?` which returns `nil` instead of raising an exception.
+
+This is ideal when you want to avoid an error being raised. 
+This can benefit performance since it doesn't have to create a stack trace and, if setup correctly, could make the code safer.


Out of curiosity, how would not using an error/exception improve safety?

Part of that text is based of: https://crystal-lang.org/reference/1.13/syntax_and_semantics/exception_handling.html#alternative-ways-to-do-error-handling.

But using for example nil instead of throwing errors, so will the compiler make you handle nil meanwhile if you have code which throws error the compiler will not make you handle that instead if you are unlucky could make your application just halt execution.

meatball133 and others added 6 commits June 30, 2024 20:55

start

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Add exercise and concept

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More work

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Update concept text

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Update config

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Format spec file

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ryanplusplus requested changes Aug 11, 2024

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Update based on feedback

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ryanplusplus approved these changes Aug 12, 2024

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Merge branch 'main' into add-errors-concept

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ryanplusplus merged commit d7c3b0a into exercism:main Aug 12, 2024
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Add errors concept #686

Add errors concept #686

meatball133 commented Aug 10, 2024

ryanplusplus Aug 11, 2024

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ryanplusplus Aug 11, 2024

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meatball133 Aug 11, 2024

		@@ -0,0 +1,5 @@
		{
		"blurb": "Crystal has modules which can be used for namespacing and organizing code. It can also be used to create mixins and to extend classes.",

	There are several built-in exceptions in Crystal, like `ArgumentError`, `IndexError`, `KeyError`, `IOError`, `SystemCallError`, `TypeError`, `ZeroDivisionError` and many more, these require you to pass a message to the exception.
	There are several built-in exceptions in Crystal, like `ArgumentError`, `IndexError`, `KeyError`, `IOError`, `SystemCallError`, `TypeError`, `ZeroDivisionError` and many more.
	These require you to pass a message to the exception.

		We wouldn't want our program to crash when an exception is raised.

		Therefore, when we know a piece of code is error prone, we can wrap it in a `begin` block and rescue the exception with a `rescue` block.


		## Method convention

		If you have checked, specific methods have two versions, one with `!` and the other without.

	If you have checked, specific methods have two versions, one with `!` and the other without.
	Some methods have two versions, one with `!` and the other without.

	- Since you want to return early in case of an error in Go, you first check whether the number of cows is less or equal than 0 with an if-statement.
	- Since you want to return early in case of an error, you first check whether the number of cows is less or equal than 0 with an if-statement.

	The library exposes a class that fulfils the following interface.
	The library exposes a class that fulfills the following interface.


		## 3. Improve the error handling

		Checking the number of cows before passing it along was a good move but you are not quite happy with the unspecific error message.

	The custom error should hold the number of cows (`Int32`) and a custom message (`String`) and the `Expection` method should serialize the data in the following format:
	The custom error should hold the number of cows (`Int32`) and a custom message (`String`), and the `Expection` method should serialize the data in the following format:

Add errors concept #686

Add errors concept #686

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meatball133 commented Aug 10, 2024

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