We need a function which creates a file with a temporary name where we have access to the name and can close and reopen the file. We have std.stdio.tmpfile, which calls the C tmpfile function and gives us a temporary file, but we have no access to the name of the file, and it gets deleted when its closed, which is completely useless for many situations, especially in unit tests where you need to do something like write to a file, close it, and then read from it. POSIX's mkstemp does something similar to this, but on some systems, it doesn't allow for very many file names (e.g. the windows implementation is restricted to 26; some POSIX implementations have similar limitations), and it doesn't provide any control over where the file is written to. So, I propose that we create something like static File tempFile(string prefix = "", string dir = tempDir()) {...} in std.stdio.File which allows for adding a prefix like mkstemp does but also allows control over where the file goes and does not have the same limitations on the number of randomly generated files as mkstemp sometimes does. And, of course, it's a normal File which won't delete itself when being closed, so it will be able to be used like any other File, unlike the one returned by std.stdio.File.tmpfile. And with that added, I'd suggest that we deprecate tmpfile, since IMHO it's pretty useless, and it'll reduce confusion if there's only one function returns a temporary file with a randomly generated name, but that's obviously up for debate.
You forgot suffix argument :). It's missing for ages, we just needed it for dub https://github.com/D-Programming-Language/dub/pull/497#issuecomment-72763326. The python implementation takes a reasonable approach, generate random names and try to exclusively open the file. https://github.com/python/cpython/blob/1196330dedbe741f8a0c418abcd2956fad29837f/Lib/tempfile.py#L191 The new function could be called namedTempFile. It's still useful to have a tempFile function that directly unlink the file.
(In reply to Martin Nowak from comment #1) > You forgot suffix argument :). What suffix? As suggested, it takes an optional prefix and randomly generates the rest. You mean that it should take an extension? Or do you think that it should take a suffix rather than a prefix? I suppose that if it takes a suffix rather than a prefix, the extension could just be part of the suffix. > It's missing for ages, we just needed it for dub > https://github.com/D-Programming-Language/dub/pull/497#issuecomment-72763326. > > The python implementation takes a reasonable approach, generate random names > and try to exclusively open the file. > > https://github.com/python/cpython/blob/ > 1196330dedbe741f8a0c418abcd2956fad29837f/Lib/tempfile.py#L191 > > The new function could be called namedTempFile. It's still useful to have a > tempFile function that directly unlink the file. I have a working implementation for Linux. The problem is that I can't figure out how to get _wsopen or any of its relatives to work on Windows. The linker fails to find them, even when I verify that they're in snn.lib (or whatever the name of the library is with the stdio stuff in it that comes with dmc). So, I'm not quite sure what to do. I could easily create a PR, but it's kind of pointless if it doesn't work on Windows. As for keeping tmpfile, I suppose that we could - to avoid forcing anyone to change their code if nothing else - but in my experience, the function is utterly useless. And replacing it with tempFile would be trivial. instead of auto file
Drat. I managed to post by accident. In any case, tmpfile could easily be replaced such that auto file = File.tmpfile(); became auto file = File.tempFile(); scope(exit) std.file.remove(file.name); so IMHO tmpfile becomes redundant on top of being pretty useless. But it _does_ mean deprecating it if we're getting rid of it, so it might be better to just keep it around rather than dealing with that.
(In reply to Jonathan M Davis from comment #3) > auto file = File.tempFile(); > scope(exit) std.file.remove(file.name); There is a security aspect, because the current tempfile is unlinked at the moment it's created. So no other process can access it. But as that's the advanced use-case it deserves the longer name, anonTempFile or so.
> What suffix? As suggested, it takes an optional prefix and randomly generates the rest. You mean that it should take an extension? Yes, prefix and suffix, random in between.
A mkdtemp for directories is missing as well.
Okay. I now have a pull request for this, and I added a suffix parameter to what I had so that now both a prefix and suffix can be set: https://github.com/D-Programming-Language/phobos/pull/2956
Commits pushed to master at https://github.com/D-Programming-Language/druntime https://github.com/D-Programming-Language/druntime/commit/0f389cb0aa5a8f5fd1a36dbdd338f1560d08ee73 Add declaration for _wsopen. It's needed for issue# 13996. https://github.com/D-Programming-Language/druntime/commit/af9cabcd48a4fef66213ad84e4eaf8959ce36306 Merge pull request #1154 from jmdavis/_wsopen Add declaration for _wsopen. It's needed for issue# 13996.
Commits pushed to 2.067 at https://github.com/D-Programming-Language/druntime https://github.com/D-Programming-Language/druntime/commit/0f389cb0aa5a8f5fd1a36dbdd338f1560d08ee73 Add declaration for _wsopen. It's needed for issue# 13996. https://github.com/D-Programming-Language/druntime/commit/af9cabcd48a4fef66213ad84e4eaf8959ce36306 Merge pull request #1154 from jmdavis/_wsopen
Commits pushed to master at https://github.com/D-Programming-Language/phobos https://github.com/D-Programming-Language/phobos/commit/e3e9f2965f438170157338767700bc1d7292dd67 Implement issue# 13996. Add File.scratchFile. This adds a File.scratchFile, which generates a random file name and returns an open std.stdio.File for it. Unlike with File.tmpfile, it's a normal file which is _not_ deleted when the file is closed, and you actually have access to the file's name, which is necessary in many situations - particularly when writing unit tests that need to write to a file and then read from it. https://github.com/D-Programming-Language/phobos/commit/8a65ff8db444f35f6322debbb970166b8c587beb Merge pull request #2956 from jmdavis/tempFile Implement issue# 13996. Add File.tempFile.
Commit pushed to revert-2956-tempFile at https://github.com/D-Programming-Language/phobos https://github.com/D-Programming-Language/phobos/commit/8087f354414ed39f23eec94049a1a154fcbb412c Revert "Implement issue# 13996. Add File.tempFile."
Commits pushed to master at https://github.com/D-Programming-Language/phobos https://github.com/D-Programming-Language/phobos/commit/8087f354414ed39f23eec94049a1a154fcbb412c Revert "Implement issue# 13996. Add File.tempFile." https://github.com/D-Programming-Language/phobos/commit/c8c5a3255def4274dcc807e479f5aca1f8177cdf Merge pull request #3273 from D-Programming-Language/revert-2956-tempFile Revert "Implement issue# 13996. Add File.tempFile."
the pull seems to cause this regression: https://issues.dlang.org/show_bug.cgi?id=14828
(In reply to Timothee Cour from comment #13) > the pull seems to cause this regression: > https://issues.dlang.org/show_bug.cgi?id=14828 I'm not sure how it could be, since it was reverted. Maybe the changes for scratchFile triggered that bug, were reverted, and now something later is triggering it. I don't know. But since the changes for this were already reverted, it's not like we can revert them to fix the regression.
Commits pushed to dmd-cxx at https://github.com/dlang/phobos https://github.com/dlang/phobos/commit/e3e9f2965f438170157338767700bc1d7292dd67 Implement issue# 13996. Add File.scratchFile. https://github.com/dlang/phobos/commit/8a65ff8db444f35f6322debbb970166b8c587beb Merge pull request #2956 from jmdavis/tempFile https://github.com/dlang/phobos/commit/8087f354414ed39f23eec94049a1a154fcbb412c Revert "Implement issue# 13996. Add File.tempFile." https://github.com/dlang/phobos/commit/c8c5a3255def4274dcc807e479f5aca1f8177cdf Merge pull request #3273 from D-Programming-Language/revert-2956-tempFile