strip does not take predicate functions.

[sbromberger]

From strip's docstring (emphasis mine):

The optional chars argument specifies which characters to remove: it can be a single character, vector or set of characters, or a predicate function.

However:

julia> a = "hello!"
"hello!"

julia> strip(a, ispunct)
ERROR: MethodError: no method matching rstrip(::String, ::typeof(ispunct))

(note the error is in rstrip, not strip.)

julia> methods(strip)
# 2 methods for generic function "strip":
[1] strip(s::AbstractString) in Base at strings/util.jl:214
[2] strip(s::AbstractString, chars) in Base at strings/util.jl:215

julia> methods(rstrip)
# 3 methods for generic function "rstrip":
[1] rstrip(s::AbstractString) in Base at strings/util.jl:194
[2] rstrip(f, s::AbstractString) in Base at strings/util.jl:189
[3] rstrip(s::AbstractString, chars::Union{AbstractChar, Tuple{Vararg{AbstractChar,N} where N}, Set{#s55} where #s55<:AbstractChar, AbstractArray{#s56,1} where #s56<:AbstractChar}) in Base at strings/util.jl:195

julia> versioninfo()
Julia Version 1.0.3
Commit 099e826241 (2018-12-18 01:34 UTC)
Platform Info:
  OS: macOS (x86_64-apple-darwin18.2.0)
  CPU: Intel(R) Core(TM) i5-3210M CPU @ 2.50GHz
  WORD_SIZE: 64
  LIBM: libopenlibm
  LLVM: libLLVM-6.0.0 (ORCJIT, ivybridge)

Edited to add: even if you put the predicate function first, strip doesn't work.

[ararslan]

Looks like lstrip and rstrip got methods with a predicate function (as the first argument, per convention), but strip was omitted. Should be non-breaking to add such a method, so we could do it in 1.x, but in the meantime we should fix the 1.0 docs to not suggest that such a method exists for strip.