@edit on Windows using default editor

[GregPlowman]

Issue discussed on Discourse https://discourse.julialang.org/t/edit-on-windows/1695

As an example @edit cmp(1,2) uses

cmd = `cmd /c start /b $path`

which runs the command:

cmd /c start /b 'C:\Program Files\Julia-0.5.0\bin\../share\julia\base\operators.jl'

I think there are two issues here for the default on Windows:

1. The space in file path: start tries run C:\Program. I tried many variations of extra quoting with single and double quotes but couldn't get it to work.
2. The forward slash in path (../share)

A workaround is:

cmd = `cmd /c start /b /D $(realpath(dirname(path))) $(basename(path))`

which runs the command:

cmd /c start /b /D 'C:\Program Files\Julia-0.5.0\share\julia\base' operators.jl

For some reason the space is OK in directory /D, realpath removes the forward slash.

Regarding the forward slash, comment from @nalimilan:

This path indeed comes from base/build_h.jl and is computed at compile time by the contrib/relative_path.sh script. I'm not sure what's the best solution to fix this: either improve the script to detect Windows or fix the path later from Julia. Could you file an issue on GitHub to discuss the best approach?

[stevengj]

The spaces issue is an annoyance of Windows: the Win32 API only allows you to pass a single string for the command-line arguments (rather than passing one string per argument as in Unixy operating systems), and you have to guess at how the program breaks this strings into tokens.

See this blog entry, for example.

In particular, if the start program is parsing its command-line in a nonstandard way, we could maybe use the windows_verbatim option to Cmd (#13780) so that we can adjust the string "manually" according to whatever start needs.

[stevengj]

This stackoverflow thread says it is a known bug in the start command and gives some workarounds.

[stevengj]

According to stackoverflow, cmd = `cmd /c start /b "" $path` should work?

[GregPlowman]

According to stackoverflow, cmd = cmd /c start /b "" $path should work?

Yes this works for me (Windows 10, I can test on Window 7 later).
It works when path contains spaces and forward slashes.

[stevengj]

Great! Could you submit a PR?

[stevengj]

Although according to the blog article linked above, we are supposed to put ^ before " and other special characters when passing quoted strings to cmd.exe.

[vtjnash]

dup #7107.

at some level, it's probably easier just to write a non-buggy start.exe program than deal with cmd's incomplete quoting rules; it's just a thin wrapper for calling ShellExecuteEx https://msdn.microsoft.com/en-us/library/windows/desktop/bb762154(v=vs.85).aspx from the command line.

[GregPlowman]

According to stackoverflow, cmd = cmd /c start /b "" $path should work?

It also works on Windows 7.

The following also works, but note that realpath() is required to convert forward slashes to back slashes.

cmd = `explorer $(realpath(path))`

Great! Could you submit a PR?

Sure, I can create a PR with cmd = `cmd /c start /b "" $path`
(since it doesn't have the issue with forward slashes, and we don't yet have a "non-buggy start.exe")

1. If so, there is a related PR for adding Notepad++ support to @edit Add Notepad++ support for @edit #20416
   Should I add it to that PR or create a new one?

2. Do we need a separate issue regarding backslashes? Could this be a problem elsewhere?

This path indeed comes from base/build_h.jl and is computed at compile time by the contrib/relative_path.sh script. I'm not sure what's the best solution to fix this: either improve the script to detect Windows or fix the path later from Julia. Could you file an issue on GitHub to discuss the best approach?

[StefanKarpinski]

This is why we avoid going through a shell at all on UNIX systems – it's nothing but pain and suffering for no gain whatsoever. I think what @vtjnash suggested is a good path forward. @vtjnash, any chance you're willing to do that?

[vtjnash]

I only have a finite amount of time to deal with adding enough hacks to get Windows to be almost feature-complete with Unix. However, since we already have a getopt implementation at https://github.com/JuliaLang/julia/blob/30bf89f3d8e564b588b8e48993e92a551b384f2c/src/getopt.h, any sufficiently motivated developer should be able to make a new repo and start populating it with better implementations of the basic command line tools (starting with a start.exe replacement).

[StefanKarpinski]

I only have a finite amount of time to deal with adding enough hacks to get Windows to be almost feature-complete with Unix.

LOL

[stevengj]

I just tried:

ShellExecute(op, file) =
    ccall((:ShellExecuteW,"shell32"), Int, (Ptr{Void}, Cwstring, Cwstring, Ptr{Void}, Ptr{Void}, Cint),
          C_NULL, op, file, C_NULL, C_NULL, 10)

and ShellExecute("open", filename) seems to work.

[vtjnash]

cmd = explorer $(realpath(path))

I just saw this. Let's do this instead of cmd start. I forgot that explorer is just a thin wrapper around ShellExecuteEx, but it seems like this should work.