Ability to write to dot files

[fabien-marty]

Context

Many thanks for this project, I love it (and I'm a big fan of import-linter too)!

I would like to automatically generate architecture diagrams in markdown (+ svg) once a day for some of my professional projects.
import-linter is great to enforce the architecture but impulse is IMHO great for discovering the architecture.

drawgraph is great as an interactive tool but here I would like to build / download SVG diagrams at a CI level (triggered once a day)

As you dropped the "image magick" dependency, I don't propose a savesvg subcommand but a savedot subcommand (I would deal with the DOT => SVG transformation externally).

CLI

The CLI could be something like that:

Options:
  --show-import-totals   Label arrows with the number of imports they
                         represent.
  --show-cycle-breakers  Identify a set of dependencies that, if removed,
                         would make the graph acyclic, and display them as
                         dashed lines.
  --filepath Filepath to use for saving the dotfile (if not set, the standard output if used)
  --help                 Show this message and exit.

=> Would you be interested in such an addition?
(If yes, I think I can propose a PR about it)

[seddonym]

I agree, this would be a good feature - thanks for suggesting it.

Rather than add a new command, I think a good API would be to combine two independent behaviours which can be composed differently:

1. The format that drawgraph outputs: supports dot and html (the default).
2. Whether it writes the output to a temporary file and opens in a browser (in interactive mode) or writes to stdout (when not in interactive mode). This would allow users to redirect the content to file. That would be slightly simpler to implement and the user gets nice things like autocomplete.

Examples:

# Opens a dot file in a browser
impulse drawgraph mypackage --format=dot
# Writes a dot file to `graph.dot`
impulse drawgraph mypackage --format=dot > graph.dot
# Writes an html file to `graph.html`
impulse drawgraph mypackage > graph.html

We can detect interactive mode using sys.stdout.isatty(). When a user is redirecting the output, that will return False.

What do you think?

[fabien-marty]

It sounds good! Thanks!

BTW, secondly, I would also be interested in a mermaid output:
impulse drawgraph mypackage --format=mermaid > graph.mermaid

=> but let's try to propose a first PR about that!

[fabien-marty]

@seddonym, if you can have a look to: #31

(I still need to add a few more tests but just to make sure it's exactly how you imagined it.)

Thanks!

[seddonym]

Thanks, I'll take a look this week.