From: knu@...
Date: 2015-12-14T14:59:08+00:00
Subject: [ruby-core:72116] [Ruby trunk - Feature #11814] String#valid_encoding? without force_encoding

Issue #11814 has been updated by Akinori MUSHA.


Martin D��rst wrote:
> A few comments on this program:

Thanks!

> - Encoding::ASCII_8BIT will pick up garbage. Encoding::US_ASCII is much better.

Maybe not.  You could choose to perform the CAP encoding when the encoding was unknown (ASCII_8BIT), or just use the binary garbage as is if the storage was capable of saving binary file names (like ZFS).

> - Encoding::ISO_8859_1 is always valid, for all bytes, so ASCII8BIT (or US-ASCII) never get used.

Ah, so true.  It���s my bad.  Anyway I put ASCII_8BIT as a sentinel so `encoding` would never be nil, so US_ASCII was not an option.

> - There are many more encodings, but distinguishing them is difficult/impossible with this method.

I know, but in most cases you have some idea as to what the possible encodings are and it is sufficient to try just a few encodings in such cases.  This example was meant to be one of them.

If you need more, a BOM-based encoding detector could be another use case for valid_encoding?(enc), I don't know.

I already named a few gems for serious use, so please don't be so strict about these casual use cases.

----------------------------------------
Feature #11814: String#valid_encoding? without force_encoding
https://bugs.ruby-lang.org/issues/11814#change-55534

* Author: Usaku NAKAMURA
* Status: Rejected
* Priority: Normal
* Assignee: 
----------------------------------------
Now we have to set a encoding to a string to validate it, just like:

```ruby
str.force_encoding('euc-jp').valid_encoding?  # => true or false
```

But to modify the string is not so smart.
knu-san requires the way to validate a string without modifiing it [*1].

Then, I propose to add an optional encoding parameter to `String#valid_encoding?`.

```ruby
str.valid_encoding?('euc-jp')  # => true or false
```

A patch is attached.

[*1] https://twitter.com/knu/status/676009662655934465 (in Japanese)

---Files--------------------------------
valid_encoding.patch (4.4 KB)


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