changelog.md

v1.4.0 - yyyy-mm-dd

Standard library additions and changes

• Added xmltree.newVerbatimText support create style's,script's text.

• uri adds Data URI Base64, implements RFC-2397.

• Add DOM Parser to the dom module for the JavaScript target.

• The default hash for Ordinal has changed to something more bit-scrambling. import hashes; proc hash(x: myInt): Hash = hashIdentity(x) recovers the old one in an instantiation context while -d:nimIntHash1 recovers it globally.

• deques.peekFirst and deques.peekLast now have var Deque[T] -> var T overloads.

• File handles created from high-level abstractions in the stdlib will no longer be inherited by child processes. In particular, these modules are affected: asyncdispatch, asyncnet, system, nativesockets, net and selectors.

  For asyncdispatch, asyncnet, net and nativesockets, an inheritable flag has been added to all procs that create sockets, allowing the user to control whether the resulting socket is inheritable. This flag is provided to ease the writing of multi-process servers, where sockets inheritance is desired.

  For a transistion period, define nimInheritHandles to enable file handle inheritance by default. This flag does not affect the selectors module due to the differing semantics between operating systems.

  asyncdispatch.setInheritable, system.setInheritable and nativesockets.setInheritable is also introduced for setting file handle or socket inheritance. Not all platform have these procs defined.

• The file descriptors created for internal bookkeeping by ioselector_kqueue and ioselector_epoll will no longer be leaked to child processes.

• strutils.formatFloat with precision = 0 has been restored to the version 1 behaviour that produces a trailing dot, e.g. formatFloat(3.14159, precision = 0) is now 3., not 3.

• critbits adds commonPrefixLen.

• relativePath(rel, abs) and relativePath(abs, rel) used to silently give wrong results (see #13222); instead they now use getCurrentDir to resolve those cases, and this can now throw in edge cases where getCurrentDir throws. relativePath also now works for js with -d:nodejs.

• JavaScript and NimScript standard library changes: streams.StringStream is now supported in JavaScript, with the limitation that any buffer pointers used must be castable to ptr string, any incompatible pointer type will not work. The lexbase and streams modules used to fail to compile on NimScript due to a bug, but this has been fixed.

  The following modules now compile on both JS and NimScript: parsecsv, parsecfg, parsesql, xmlparser, htmlparser and ropes. Additionally supported for JS is cstrutils.startsWith and cstrutils.endsWith, for NimScript: json, parsejson, strtabs and unidecode.

• Added streams.readStr and streams.peekStr overloads to accept an existing string to modify, which avoids memory allocations, similar to streams.readLine (#13857).

• Added high-level asyncnet.sendTo and asyncnet.recvFrom. UDP functionality.

• paramCount & paramStr are now defined in os.nim instead of nimscript.nim for nimscript/nimble.

• dollars.$ now works for unsigned ints with nim js

• Improvements to the bitops module, including bitslices, non-mutating versions of the original masking functions, mask/masked, and varargs support for bitand, bitor, and bitxor.

• sugar.=> and sugar.-> changes: Previously (x, y: int) was transformed into (x: auto, y: int), it now becomes (x: int, y: int) in consistency with regular proc definitions (although you cannot use semicolons).

  Pragmas and using a name are now allowed on the lefthand side of =>. Here is an aggregate example of these changes:

  import sugar
  
  foo(x, y: int) {.noSideEffect.} => x + y
  
  # is transformed into
  
  proc foo(x: int, y: int): auto {.noSideEffect.} = x + y

• The fields of times.DateTime are now private, and are accessed with getters and deprecated setters.

• The times module now handles the default value for DateTime more consistently. Most procs raise an assertion error when given an uninitialized DateTime, the exceptions are == and $ (which returns "Uninitialized DateTime"). The proc times.isInitialized has been added which can be used to check if a DateTime has been initialized.

• Fix a bug where calling close on io streams in osproc.startProcess was a noop and led to hangs if a process had both reads from stdin and writes (eg to stdout).

• The callback that is passed to system.onThreadDestruction must now be .raises: [].

• The callback that is assigned to system.onUnhandledException must now be .gcsafe.

• osproc.execCmdEx now takes an optional input for stdin.

• osproc.execCmdEx now takes an optional input for stdin, workingDir and env parameters.

Language changes

• In the newruntime it is now allowed to assign discriminator field without restrictions as long as case object doesn't have custom destructor. Discriminator value doesn't have to be a constant either. If you have custom destructor for case object and you do want to freely assign discriminator fields, it is recommended to refactor object into 2 objects like this:

  type
    MyObj = object
      case kind: bool
        of true: y: ptr UncheckedArray[float]
        of false: z: seq[int]
  
  proc `=destroy`(x: MyObj) =
    if x.kind and x.y != nil:
      deallocShared(x.y)
      x.y = nil

  Refactor into:

  type
    MySubObj = object
      val: ptr UncheckedArray[float]
    MyObj = object
      case kind: bool
      of true: y: MySubObj
      of false: z: seq[int]
  
  proc `=destroy`(x: MySubObj) =
    if x.val != nil:
      deallocShared(x.val)
      x.val = nil

• getImpl() on enum type symbols now returns field syms instead of idents. This helps with writing typed macros. Old behavior for backwards compatiblity can be restored with command line switch --useVersion:1.0.

• let statements can now be used without a value if declared with importc/importcpp/importjs/importobjc.

• The keyword from is now usable as an operator.

• Exceptions inheriting from system.Defect are no longer tracked with the .raises: [] exception tracking mechanism. This is more consistent with the built-in operations. The following always used to compile (and still does):

proc mydiv(a, b): int {.raises: [].} =
  a div b # can raise an DivByZeroDefect

Now also this compiles:

proc mydiv(a, b): int {.raises: [].} =
  if b == 0: raise newException(DivByZeroDefect, "division by zero")
  else: result = a div b

The reason for this is that DivByZeroDefect inherits from Defect and with --panics:on Defects become unrecoverable errors.

Compiler changes

• Specific warnings can now be turned into errors via --warningAsError[X]:on|off.
• The define and undef pragmas have been de-deprecated.
• New command: nim r main.nim [args...] which compiles and runs main.nim, and implies --usenimcache so that output is saved to $nimcache/main$exeExt, using the same logic as nim c -r to avoid recompiling when sources don't change. This is now the preferred way to run tests, avoiding the usual pain of clobbering your repo with binaries or using tricky gitignore rules on posix. Example:

  nim r compiler/nim.nim --help # only compiled the first time
  echo 'import os; echo getCurrentCompilerExe()' | nim r - # this works too
  nim r compiler/nim.nim --fullhelp # no recompilation
  nim r --nimcache:/tmp main # binary saved to /tmp/main

• --hint:processing is now supported and means --hint:processing:on (likewise with other hints and warnings), which is consistent with all other bool flags. (since 1.3.3).
• nim doc -r main and nim rst2html -r main now call openDefaultBrowser
• new hint: --hint:msgOrigin will show where a compiler msg (hint|warning|error) was generated; this helps in particular when it's non obvious where it came from either because multiple locations generate the same message, or because the message involves runtime formatting.
• new flag `--backend:js|c|cpp|objc (or -b:js etc), to change backend; can be used with any command (eg nim r, doc, check etc); safe to re-assign.
• new flag --doccmd:cmd to pass additional flags for runnableExamples, eg: --doccmd:-d:foo --threads use --doccmd:skip to skip runnableExamples and rst test snippets.
• new flag --usenimcache to output to nimcache (whatever it resolves to after all commands are processed) and avoids polluting both $pwd and $projectdir. It can be used with any command.
• runnableExamples "-b:cpp -r:off": code is now supported, allowing to override how an example is compiled and run, for example to change backend or compile only.

Tool changes