NoMethodError: undefined method `write' for MemFs::File:Class

[rmm5t]

I know that the lack of a IO.write implementation is a known issue in the README still, but the more basic usage of it, typically written as File.write(filename, string), is something that compliments the typical File.read(filename) quite nicely.

In my test suite, for now, I'm just manually adding a MemFs::File.write method to cover the usage I was using in my project.

class MemFs::File
  # MemFs doesn't implement IO.write, because the base implementation allows
  # for file offsets and other options, but it's quite convenient to be able
  # to use File.write in its most basic use case, so let's simulate that.
  def self.write(name, string, offset = nil, open_args = {})
    File.open(name, "w") { |f| f.write(string) }
  end
end

I just wanted to open up a discussion about potentially implementing this in memfs. I understand that this is not a complete implementation. I also understand the complexities involved with fully implementing offset and open_args support.

Right now, I'm at a cross-roads, because I ran into some semi-serious troubles with FakeFS and open-uri. I decided to try MemFs. It seems to work great so far, but I ran into this File.write hurdle. I'm now considering dropping a fake filesystem from my test suite altogether, but if I decide to keep MemFs around, I'd be willing to look deeper into a full PR here.

If this isn't worth doing, feel free to close this issue, but I wanted document this, open a discussion, and share (in case any one else might benefit from this).

[simonc]

Hi @rmm5t ! :)

Thank you for your interest in the project. It's definitely a thing that should be addressed. And a basic implementation that covers some options is still better than none.

If you want to give a shot at a PR I would gladly help you.

As a matter of documentation, I'll indicate here that the implementation should take place in the MemFs::IO::ClassMethods module :)

[houndci-bot]

Line is too long. [87/80]

[rmm5t]

@simonc I gave this a quick shot and converted this issue into a pull-request. Please review.

It still doesn't support offsets, but it supports the most basic case of writing a plain string to a file. e.g.:

File.write "myfile.txt", "my contents"

[rmm5t]

Prefer double-quoted strings unless you need single quotes to avoid extra backslashes for escaping.

Heh. I tried to match the project's coding conventions even though the warnings from houndci better match my own preferred conventions better. Oh well. I tried.

[simonc]

@rmm5t Thanks :) I will review this and we'll go forward.

Don't worry about HoundCI, I just haven't found the time to set it up according to the project. But I think I used rubocop for this one :)

[simonc]

Well it seems I forgot to bind a specific version of Rubocop to the project so now it's all warnings and all. I'll have some cleanup to do in the codebase :)

[simonc]

@rmm5t I think the method args handling could be lighter. By explicitly naming the arguments like the ones of IO::write it should be easier to deal with.

Would you be ok with trying with def write(path, string, offset = 0, open_args = {}) ?
Thanks a lot :)

[simonc]

Oh and I try to keep the methods organized by alphabetical order. There are so many of them, it's easier to find your way :D

[houndci-bot]

Line is too long. [84/80]

[rmm5t]

Closing and re-opening PR to trigger new Travis build. It looks like that last one borked out for bundler/rubygems reasons.

[rmm5t]

Hrm. I don't know why the build is now failing during the bundle install step for Ruby 1.9.3 and 2.1.2, but working with Ruby 2.0.0 and 2.2.2.

[simonc]

That's weird. I just pushed to master and I have the same issue, I'll look into it.

[simonc]

I'm trying to fix this Travis issue. I created a branch reverting all changes since the last successful build. If it doesn't work I guess I'll try to contact them or simply change CI… I'll keep you posted.

[simonc]

I'm not completely comfortable with this line since passing false should result in no implicit conversion from boolean (TypeError) an here it would end up being zero.

[simonc]

By the way I'm in touch with Travis' support, it's a problem with the new platform they deployed. I have a workaround for know.

[rmm5t]

@simonc I added implicit type conversion support to IO.write to cover your previous concerns

[simonc]

Merged! Thank you! 😄