deprecate readstring to read(io, String)

[JeffBezanson]

This is more consistent with other read methods, and more easily extensible to other types of strings.

[jpfairbanks]

This sounds straightforward you just:

• remove the definition of readstring
• add the new method for read(s::IO, ::Type{String})
• @deprecate in the base/deprecated.jl
• chase down all the deprecation warnings in Base
• Update the docs
• Add NEWS entry

Are there any other steps?

[JeffBezanson]

Correct!

[jpfairbanks]

This example in the docs doesn't work .

"""
    open(f::Function, args...)

Apply the function `f` to the result of `open(args...)` and close the resulting file
descriptor upon completion.

**Example**: `open(readstring, "file.txt")`
"""

You could make an anonymous function. open(f->read(f, String), "file.txt") but that looks weird.

[jpfairbanks]

Also what do you do with this line in precompile.jl

precompile(Tuple{typeof(Base.open), typeof(Base.readstring), String})
?

[JeffBezanson]

I think open(f->read(f, String), "file.txt") is fine, or maybe open(read, "file.bin") instead.

The precompile line can just be deleted; those need to be regenerated periodically anyway.

[jpfairbanks]

Ok, I went with f-read(f,String) and deleted it. The PR is open and CI failed due to some documentation building stuff. I don't know what to do about the CI.

[matklad]

Low-weight opinion of a new Julia user, but I personally would appreciate if there were Base.readstring(io) = read(io, String) alias defined.

readstring(io) is easier to type than read(io, String) and also is cognitively easier to understand -- I won't be thinking "cool, Julia can dispatch on types", the code would be just boring. This is a bit of a concrete abstraction smell, as fixing the second argument to String would be pretty common I guess.

[StefanKarpinski]

Personally, I miss readall(io) which is how this was originally spelled. Why does that spelling make sense?

1. Whereas read(io) by itself produces bytes, readline, readlines, readuntil and readchomp all produce strings, so there is strong precedent for something called readxxx producing strings.

2. Calling it readstring is a bit ambiguous since there are many ways to read a string from an IO stream, such as all of those functions. For example, it would also be arguable that something called readstring could read a NUL-terminated string from an IO stream. Julia doesn't use NUL-terminated strings, so I'm not arguing for that, but the point is that readstring and even read(io, String) are not that clear. Read a string how?

3. The key behavior of readall is that it reads all of the remaining data as a string. The fact that readxxx functions generally produce strings already implies that it produces a string; calling it readall makes that as clear as possible.

Therefore, I propose that we reinstate readall(io) as an alias for read(io, String).

[matklad]

Huh, TIL about readchomp. It actually fully replaces the need for readall for me: matklad/config@6634ca5. I didn't realize that it could exists, I think advertising it in the docs might help: #37806!

[StefanKarpinski]

readchomp is one of my favorites 😁