Temporary Files And Directories in Crystal

Crystal provides functionality for working with temporary files and directories through its standard library. Here’s how you can create and manage temporary files and directories:

require "file_utils"
require "tempfile"

# Helper function to check for errors
def check(result)
  raise result.inspect if result.is_a?(Exception)
end

# Create a temporary file
temp_file = File.tempfile("sample")
puts "Temp file name: #{temp_file.path}"

# Clean up the file after we're done
at_exit { temp_file.delete }

# We can write some data to the file
temp_file.write(Bytes[1, 2, 3, 4])
temp_file.flush

# Create a temporary directory
temp_dir = Dir.tempdir
puts "Temp dir name: #{temp_dir}"

# Clean up the directory after we're done
at_exit { FileUtils.rm_rf(temp_dir) }

# Now we can create files within the temporary directory
file_path = File.join(temp_dir, "file1")
File.write(file_path, Bytes[1, 2])

In Crystal, we use the File.tempfile method to create a temporary file. This method returns a File object that we can write to. The file is created with a unique name in the system’s temporary directory.

For creating a temporary directory, we use Dir.tempdir. This returns a string representing the path to a newly created temporary directory.

We use at_exit hooks to ensure that our temporary files and directories are cleaned up when the program exits. This is similar to using defer in other languages.

To write data to the file, we can use the write method on the File object. In this example, we’re writing a byte array.

For creating files within the temporary directory, we can use File.join to construct the full path and then File.write to create and write to the file.

Note that Crystal’s standard library provides a high-level API for these operations, making it straightforward to work with temporary files and directories.

When you run this program, you’ll see output similar to:

Temp file name: /tmp/sample20230615-12345-abcdef
Temp dir name: /tmp/crystal-run-20230615-12345-abcdef

The exact names will vary as they are generated to be unique for each run of the program.