Add g.version algorithm

[AlisterH]

Description

• Add g.version algorithm, allowing the user to check the details of the GRASS version that the GRASS processing provider is using (useful for debugging).
• Update the grass processing algorithms guide.
• Bugfix: prevent the algorithm dialog from reporting html output has been created if the user chose not to create it.
• Update g.extension.list to use QgsProcessingParameterEnum
• Save output of g.version and g.extension.list algorithms to an output string when creating html output.
  This allows code to get the actual version number:

  >>> processing.run("grass7:g.version",{'html': 'grass_version_info.html', '-r': 0, '-e':0})['GRASS_VERSIONINFO'].split()[1]
  '8.3.1'

It also allows code to install a grass addon if it isn't already installed:

  >>> alglist=processing.run("grass7:g.extension.list",{'-a': 'TRUE', 'html': 'addons_list.html'})['GRASS_ADDONS']
  >>> if 'r.stream.orderz' not in alglist.splitlines():
  ...   processing.run("grass7:g.extension.manage",{'extension': 'r.stream.order', 'operation': 0})
  {}

History

• This is an updated version of Add g.version algorithm #53635, which was closed by the bot because I didn't bump it diligently enough.
• I note that @nyalldawson labelled Add g.version algorithm #53635 as Freeze Exempt

Notes

• I would like to print out the GRASS_VERSIONINFO and GRASS_ADDONS outputs when running in the algorithm dialog, so that users know they exist. The original pull request achieved this (although they weren't listed by .algorithmHelp), but I'm not sure how I should achieve this now - I think it may be related to this part in src/core/processing/qgsprocessingfeedback.cpp:

  const QList< const QgsProcessingOutputDefinition * > outputs = algorithm->outputDefinitions();
  for ( const QgsProcessingOutputDefinition *output : outputs )

• Ideally these outputs would be created even when the user elects not to create html output, so that when running in code you don't need to create the html files. But that was too difficult for me to implement, and unless it is easier than it seemed, it would be hardly worth someone else's time to work on it.

[github-actions]

🪟 Windows builds ready!

Windows builds of this PR are available for testing here. Debug symbols for this build are available here.

(Built from commit a2a7d2e)

[AlisterH]

Notes

• I would like to print out the GRASS_VERSIONINFO and GRASS_ADDONS outputs when running in the algorithm dialog, so that users know they exist.

Having said that, I don't think there's any reason this couldn't be rectified at a later date. But if there's a preference to use one standard name such as MESSAGES it would be better to make that decision first.

The original pull request achieved this, but I'm not sure how I should achieve this now - I think it is due to this part in src/core/processing/qgsprocessingfeedback.cpp:

  const QList< const QgsProcessingOutputDefinition * > outputs = algorithm->outputDefinitions();
  for ( const QgsProcessingOutputDefinition *output : outputs )

• Ideally these outputs would be created even when the user elects not to create html output, so that when running in code you don't need to create the html files. But that was too difficult for me to implement, and unless it is easier than it seemed, it would be hardly worth someone else's time to work on it.

Actually, my first thought was that it would be good to always (for all GRASS algorithms) save the messages GRASS prints to an output called 'MESSAGES' or something, but I thought there may be a reason for an algorithm to create more than one output like this, and in any case I decided I wasn't proficient enough to mess with the code that prints the GRASS outputs to the dialog when there is no html output.

[nyalldawson]

Can you open a separate PR for this fix? It's unrelated to the grass ones

[AlisterH]

Can you open a separate PR for this fix? It's unrelated to the grass ones

#56115

[nyalldawson]

Thanks! Can you update this PR and remove that commit now?

[AlisterH]

I've reverted, squashed and force-pushed. Hopefully that's the proper way to do this!

[nyalldawson]

@AlisterH can you update this? Some of these files moved around in #56196

[AlisterH]

Done, but if I need to amend those commit messages that refer to grass7.txt I'll need to come back tomorrow to do it.