Well, all these questions came up when I started implementing a
solution, and the further I looked the higher I climbed up the branches.
I will limit the scope to string and list of strings as you suggest,
later we can extend it if necessary.
If i see the need to implement a trim_{prefix, suffix}/2 I will make it
private then.
I will create a an issue and submit a PR when I have a WIP version of a
it.
Cheers
On Wed, 2 Mar 2022 19:56:42 +0100
José Valim <jose.va...@dashbit.co> wrote:
> Sorry, I got so wrapped up on the proposal that I forgot about your
> example. :D
>
> We can make replace_leading/trailing/prefix/suffix accept t | [t] and
> that would solve your use case. We already accept only this subset on
> starts_with? / ends_with?, so I think it is a natural extension here.
>
> Then it will automatically work on trim_leading/trim_trailing, since
> those just use the replace equivalents. Shall we go this route for
> now? Please open up an issue and feel free to submit a PR. :)
>
> I am not convinced on trim_prefix/trim_suffix yet though, but you can
> use the replace functions to achieve the same.
>
> On Wed, Mar 2, 2022 at 7:11 PM 'eksperimental' via elixir-lang-core <
> elixir-lang-core@googlegroups.com> wrote:
>
> > > So unless there is a strong
> > > reason for adding this, rather than consistency, I would not go
> > > this route.
> >
> > Personally I don't think it is an inconsistency because there is no
> > equivalent of String.trim_leading/1 (or the equivalent makes no
> > sense, or hardly has any use).
> >
> > The need for String.trim_prefix/2 is because what actually solves
> > the problem (my use case) that I initially shows.
> >
> > String.trim_leading could be considered an addition for consistency,
> > but I guess it could still be useful in some cases but its
> > implementation would not be as optimal as Sting.trim_prefix/2' s.
> >
> >
> > On Wed, 2 Mar 2022 14:56:19 +0100
> > José Valim <jose.va...@dashbit.co> wrote:
> >
> > > Thanks for the proposal. I believe we don't support all patterns
> > > because it will be inefficient, especially the suffix/trailing
> > > functions. It is not necessarily trivial to implement it for
> > > regexes either (and regexes have their own mechanism to represent
> > > prefixes/suffixes).
> > >
> > > The reason we don't have "trim_prefix" and "trim_suffix" is
> > > because there is no reasonable implementation of trim_prefix/1 and
> > > trim_suffix/1 - where no pattern to trim on is given (for
> > > example, it it to the behaviour of trim_leading/1 and
> > > trim_trailing/1). So we could add trim_prefix/2 and
> > > trim_suffix/2, but then it is inconsistent with other trim*
> > > functions. So unless there is a strong reason for adding this,
> > > rather than consistency, I would not go this route.
> > >
> > >
> > >
> > > On Wed, Mar 2, 2022 at 2:25 PM 'eksperimental' via
> > > elixir-lang-core < elixir-lang-core@googlegroups.com> wrote:
> > >
> > > > When starting to work in this implementation was wondering what
> > > > should be the return value of
> > > >
> > > > String.trim_leading("--__--abc", [" ", "-", "_"])
> > > >
> > > >
> > > > and I realized that it should mimic String.replace_leading/3
> > > > Therefore it should returning "abc"
> > > >
> > > > Which leads me to think we should introduce
> > > > String.trim_prefix/2, in order to be consistent with
> > > > String.replace_prefix/3 where the same input as above should
> > > > behave like this:
> > > > iex> String.trim_prefix("--__--abc", [" ", "-", "_"])
> > > > "__--abc"
> > > >
> > > > Which also makes me think that String.replace_prefix should also
> > > > behave like String.replace/3 where the second argument (match)
> > > > is a pattern, not a string (ie. a string, list of strings, or
> > > > a compiled search pattern). By introducing this last
> > > > consistency change, the implementation of the consistency
> > > > changes for the other functions mentioned above is
> > > > straight-forward.
> > > >
> > > > So in short this consistency proposals suggests some functions
> > > > to support t:String.pattern/0 which could be a string, a list of
> > > > strings, or a compiled search pattern.
> > > >
> > > > 1. `String.replace_{leading, prefix, suffix, trailing}/3` to
> > > > support in its second argument (match) t:String.pattern/0.
> > > > Current String.replace/4 supports t:String.pattern/0 |
> > > > t:Regex.t/0, but for the sake of simplifying this proposal I
> > > > would leave out Regexes out of the equation for now.
> > > >
> > > > 2. Introduce String.trim_{prefix, suffix}/2 which will support
> > > > t:String.pattern/0 as a its second arguments. These functions
> > > > should mimic String.replace_{prefix, suffix}/2
> > > >
> > > > 3. Add support for t:String.pattern/0 for String.{trim,
> > > > trim_leading, trim_trailing}/2 to support t:String.pattern/0 as
> > > > its second argument. These functions should mimic
> > > > String.{replace, replace_leading, replace_trailing}/3
> > > >
> > > > Please let me know what you think.
> > > >
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