Re: Changing dictionary while flyspell-buffer is running

[Eli Zaretskii]

> From: Titus von der Malsburg <address@hidden>
> Cc: address@hidden, address@hidden
> Date: Thu, 21 Feb 2019 09:34:09 +0100
> 
> > Mayb I suggest to install Hunspell, then?  It supports loading several
> > dictionaries at once, and will eliminate the need to switch a
> > dictionary while spell-checking a multi-lingual document.  Emacs
> > already supports that feature of Hunspell.
> 
> Hunspell is a fantastic spell-checker.  But this approach has two
> downsides: 1. Hunspell is slow compared to ispell/aspell, which can be a
> problem with larger documents.

Hunspell is indeed about twice slower than Aspell, but:

  . both are very fast, so a factor of 2 doesn't matter in practice
  . speed only matters if you spell-check a large document with no
    misspellings at all -- as soon as there's a single misspelled
    word, marking it and selecting the correction will render any
    speed differences irrelevant.  And my typical use cases,
    spell-checking technical text, usually show quite a few "typos",
    words that are from jargon or abbreviations, which no speller will
    know about.

> 2. If you set multiple dictionaries, you
> will get false negatives since a typo in one language might be a word
> in another language.  Depending on the set of languages used, this could
> be a real problem.

It could be.  IME, it never is, as of the 3 languages I write fluently
and frequently each uses a different script, so no false negative is
ever possible.  Even when using several languages that use the same
script, say, Latin, the accented letters usually prevent false
negatives.

Of course, you also get false negatives when writing in a single
language, because some typos are actually a valid word.  The larger
the dictionary used by the speller, the higher your chances of getting
such false negatives.

Finally, guessing a language is also not 100% correct, especially when
short phrases from some language are inserted into text written in
another language, something that happens a lot in email
correspondence, for example.

The advantage of using several dictionaries simultaneously is that no
guessing is involved.