Refactor file output to use click.File and deduplicate writer logic

[shifa-khan]

Several commands duplicate the full writer block across if output / else branches when writing to a file vs stdout. This can be simplified by switching --output from clickext.ClickPath() to click.File("w") and passing io.TextIO to the export functions. This removes the need for manual open()/close() handling and eliminates the duplicated code paths.

Affected commands:
package list-versions - _export_versions_csv, _export_versions_json, _export_versions_table
list-overrides - _export_csv, _export_json
graph - constraints, to-dot
build-order
minimize

[rd4398]

@shifa-khan can we close this issue as the PR is merged?

[shifa-khan]

PR is merged for issue #1177. It added output_file_or_stdout() but only applied it to 2 functions but there are still ~12 places with the old duplicated logic. This issue also proposes click.File("w") which would replace the context manager entirely. Should have addressed both issues together to avoid this overlap.

@dhellmann @LalatenduMohanty, would you prefer adopting click.File("w") as the standard (removes the need for any manual file handling), or sticking with output_file_or_stdout()?

[dhellmann]

PR is merged for issue #1177. It added output_file_or_stdout() but only applied it to 2 functions but there are still ~12 places with the old duplicated logic. This issue also proposes click.File("w") which would replace the context manager entirely. Should have addressed both issues together to avoid this overlap.

@dhellmann @LalatenduMohanty, would you prefer adopting click.File("w") as the standard (removes the need for any manual file handling), or sticking with output_file_or_stdout()?

I'm not familiar with click.File(), what are the benefits of using that?

[shifa-khan]

I'm not familiar with click.File(), what are the benefits of using that?

It was raised here. Instead of --output giving us a file path that we open/close ourselves, click.File("w") gives us a file handle directly ready to write to. No open(), close(), Click takes care of it.

Downside is it changes --output from a path to a file handle, so every function signature that takes it would need updating. The context manager you suggested gets us most of the same benefit with less churn.