Add pub depend command

[DartBot]

<img src="https://avatars.githubusercontent.com/u/444270?v=3" align="left" width="96" height="96"hspace="10"> Issue by seaneagan
Originally opened as dart-lang/sdk#18911

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It's nice to be able to tell someone to just run a command, instead of "add a foo dependency to your pubspec.yaml", especially for new dart users, and those using an editor without special pubspec.yaml editing support.

Similar to:

  npm install <name> [--save|--save-dev|--save-optional]

Could have:

  pub depend <package> [options]

  Options:

  --version -v Version_constraint (defaults to "any")
  --source -s One of git,hosted,path) # or just derive from <package> ?
  --dev -d Put in dev_dependencies

[DartBot]

<img src="https://avatars.githubusercontent.com/u/17034?v=3" align="left" width="48" height="48"hspace="10"> Comment by kevmoo

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Removed Type-Defect label.
Added Type-Enhancement, Area-Pub, Triaged labels.

[DartBot]

<img src="https://avatars.githubusercontent.com/u/188?v=3" align="left" width="48" height="48"hspace="10"> Comment by nex3

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This would be nice, but doing it in an unobtrusive way requires more YAML formatting ability than we currently have.

[DartBot]

<img src="https://avatars.githubusercontent.com/u/2130849?v=3" align="left" width="48" height="48"hspace="10"> Comment by kaendfinger

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If I contributed encoding to the yaml module, this would be possible right? I'm about to start on that now....

[DartBot]

<img src="https://avatars.githubusercontent.com/u/2130849?v=3" align="left" width="48" height="48"hspace="10"> Comment by kaendfinger

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Wait, so how is the pubspec.lock file generated xD

[DartBot]

<img src="https://avatars.githubusercontent.com/u/444270?v=3" align="left" width="48" height="48"hspace="10"> Comment by seaneagan

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On second thought, it'd be much better to default --version (for hosted dependencies) to the same version constraints suggested in the warnings from pub publish when you have an any constraint i.e.:

1. ={latest} <{next potentially breaking semver version}

Needs some thought on which command names/options to use for what, but potentially:

    pub depend foo

adds a foo dep with 1) to your pubspec (no-op if you already have a foo dep), then later when you want to try a new potentially breaking version:

    pub upgrade foo --constraint

where --constraint means to upgrade the actual constraint in the pubspec to 1) (based on the new latest version), not just the version in your packages dir. And maybe:

    pub upgrade --constraint

to upgrade all version constraints in the pubspec to 1).

All this can then be used by the dart editor in the pubspec editing GUI (issue dart-lang/sdk#19389).

[DartBot]

<img src="https://avatars.githubusercontent.com/u/188?v=3" align="left" width="48" height="48"hspace="10"> Comment by nex3

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If I contributed encoding to the yaml module, this would be possible right? I'm about to start on that now....

That would certainly help. It would be important that the encoding be powerful enough to add to the file while minimally changing the existing formatting, though.

Wait, so how is the pubspec.lock file generated xD

It's formatted manually, since it's relatively uniform in structure and we don't need to preserve users' edits.

[DartBot]

<img src="https://avatars.githubusercontent.com/u/2130849?v=3" align="left" width="48" height="48"hspace="10"> Comment by kaendfinger

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Ok, I'll get started on it

[DartBot]

<img src="https://avatars.githubusercontent.com/u/1081711?v=3" align="left" width="48" height="48"hspace="10"> Comment by jmesserly

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Was just searching for this, after having a pleasant experience with the NPM equivalent. Would be great to have this in Pub!

Another related command: npm inithttps://www.npmjs.org/doc/cli/npm-init.html

[DartBot]

<img src="https://avatars.githubusercontent.com/u/444270?v=3" align="left" width="48" height="48"hspace="10"> Comment by seaneagan

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I'm starting to work on this (and other functionality for editing pubspecs) here:

https://pub.dartlang.org/packages/den

[nex3]

At this point pub has a pretty clear policy against writing to user-authored files. I think den is the right place for this.