# v2.2.0 - yyyy-mm-dd


## Changes affecting backward compatibility

- `-d:nimStrictDelete` becomes the default. An index error is produced when the index passed to `system.delete` was out of bounds. Use `-d:nimAuditDelete` to mimic the old behavior for backwards compatibility.
- The default user-agent in `std/httpclient` has been changed to `Nim-httpclient/<version>` instead of `Nim httpclient/<version>` which was incorrect according to the HTTP spec.
- Methods now support implementations based on a VTable by using `--experimental:vtables`. Methods are then confined to be in the same module where their type has been defined.
- With `-d:nimPreviewNonVarDestructor`, non-var destructors become the default.

## Standard library additions and changes

[//]: # "Changes:"

- Changed `std/osfiles.copyFile` to allow to specify `bufferSize` instead of a hardcoded one.
- Changed `std/osfiles.copyFile` to use `POSIX_FADV_SEQUENTIAL` hints for kernel-level aggressive sequential read-aheads.
- `std/htmlparser` has been moved to a nimble package, use `nimble` or `atlas` to install it.

[//]: # "Additions:"

- Added `newStringUninit` to system, which creates a new string of length `len` like `newString` but with uninitialized content.
- Added `setLenUninit` to system, which doesn't initalize
slots when enlarging a sequence.
- Added `hasDefaultValue` to `std/typetraits` to check if a type has a valid default value.
- Added Viewport API for the JavaScript targets in the `dom` module.

[//]: # "Deprecations:"

- Deprecates `system.newSeqUninitialized`, which is replaced by `newSeqUninit`.

[//]: # "Removals:"


## Language changes

- `noInit` can be used in types and fields to disable member initializers in the C++ backend. 
- C++ custom constructors initializers see https://nim-lang.org/docs/manual_experimental.htm#constructor-initializer
- `member` can be used to attach a procedure to a C++ type.
- C++ `constructor` now reuses `result` instead creating `this`.

## Compiler changes

- `--nimcache` using a relative path as the argument in a config file is now relative to the config file instead of the current directory.

## Tool changes

- koch now allows bootstrapping with `-d:nimHasLibFFI`, replacing the older option of building the compiler directly w/ the `libffi` nimble package in tow.