Return true/false from Task#invoke / #execute / ...

[nixpulvis]

I'm currently building a rake task that needs to call a few other rake tasks at specific times in the middle of itself. There is a bit of logic around what tasks to run based on the success of the former tasks. Right now I don't have access to information about the success of tasks run with Rake::Task['name'].invoke. I'd love to see this functionality added.

[drbrain]

Why don't you use the task's dependencies?

A task can choose to run or not (such as a FileTask) and dependencies maintain ordering.

[drbrain]

Also, if you need to run tasks "in the middle" of another task it sounds like your tasks are too big and should be broken up into smaller pieces.

[nixpulvis]

Well I don't have control of the other tasks. To give you a better idea, here's what I'm trying to do. It's within a rails app.

I'm writing something that drops my database using rake db:drop then rake db:create and rake db:migrate then goes off and loads production data from S3 backup.

Thing is I want to wait on the loading of the production database if dropping fails.

[drbrain]

This doesn't work?

task 'db:load_production' => %w[db:drop db:create db:migrate] do
  # …
end

[nixpulvis]

I want to backup my local database first. I guess you could argue I should make a task for that. So that's what I'm doing now. But I still feel this is something worth doing possibly, considering the return value of these methods is pretty useless right now.

[drbrain]

Yes, you should use a task for that:

task 'db:load_production' => %w[db:backup db:drop db:create db:migrate] do
  # …
end

Returning status information from rake's internals seems like it encourages incorrect creation of rake tasks. I'm not convinced this is a good feature yet, especially when it seems "use tasks" fixes the problem and is more flexible overall.

[damphyr]

You have to keep in mind that a task that does not succeed raises an exception. At least that's how it should be. This means that an unsuccessful task will interrupt your rake run anyway.

What I usually do if I want to for example run a bunch of tasks and at the end report on any errors is to loop the invoke calls with a begin/rescue block and collect any failures.

A sequence of

Task['bar'].invoke
Task['bas'].invoke
Task['foo'].invoke

is equivalent to

task :foo =>['bar','bas']

actually, not quite - if bar or bas have prerequisites then the task version might reorder the prerequisite execution)

[nixpulvis]

I guess I'm more in favor of the "UNIX" way. What with return codes and all.

[drbrain]

I am going to reject this since it allows you to use tasks in non-rake-like ways.