Series and parallel projects.
 

Of all the tools I've tried, Omnifocus comes the closest to what I need: It works on a Mac, it has a somewhat lighter version for my iPod. This is going to help me make my tree farm actually work I think.

BUT I'm having trouble with series and parallel.

I've got a bunch of different contexts:
Town (errands, seeing potential customers)
Desk (Computer work, research) -- can be done in the middle of the night))
Farm (Field work, setting up infra-structure) -- limited to daylight. (And here in midwinter daylight is only 9 a.m. to 4 p.m.)
Shop (can be done at dark time, but shop is unheated, so hard to do when really cold.)
The net effect of contexts is that I jump around a lot depending on time of day, weather.

Now let's look at a project:
Farm Irrigation System:
* Water Pump
* * Research water pumps.
* * Order Water Pump
* * Install Water pump
* Water Filter
* * Research
* * Order
* * Install
* Pump house
* * Design
* * Pick up materials
* * Build
* Water Lines
* * Move existing line to new pumphouse.
* * Tie in to well as backup system.
* * BUY check valve to put between systems.

Each action group is sequential within it, and breaking it down into chunks like this is helping me face otherwise daunting tasks.

BUT: How do I show that the installation stage of the pumps and the filters has to wait for the pump house to be finished, but that the research and ordering can be parallel with the start of the pump house.

As another example: I buy a truckload of straw bales every year. Bales get used for making pens for my trees (so the pots don't blow over) I also break some down for mulch, use some for bedding. It is quite conceivable that I could have 3-4 projects that are on hold pending strawbale delivery.

Is there a way to show that several actions are dependent on a certain action being done before they can become active?

[QUOTE=sgbotsford;50941]
Is there a way to show that several actions are dependent on a certain action being done before they can become active?[/QUOTE]

The short answer is, "not yet".

Until such a feature is added, there are a couple of alternatives. One is to be a bit more liberal with how tasks are arranged. For example, in your irrigation project you could move the two install tasks into the Pump house action group, after the Build action. Of course, that assumes you've completed the research and ordering of the pump and filter. That brings us to the second alternative: Waiting For actions. You can add Waiting For actions to express dependency on completion of another project. For example, under Pump house you might have a parallel action group "Wait for parts to arrive", with actions "Wait for filter to arrive" and "Wait for pump to arrive".

In general, I find that I'm regularly rearranging the actions in my projects to express dependencies that emerge while on work on the project. I find I'm more productive if I do just enough planning to know what's next, plus anything else that comes to mind. I use daily and weekly reviews to adjust the plan as I go. This approach lessens the need to complex interproject dependencies.

When tags become available, variables like daylight and business hours can be used. If links become available, then one hierarchy can be dependent on another by sharing a task. In the meantime, I also use Waiting For context, but typically just edit the text slightly and change the Context to and from Waiting For as the need arises instead of checking the box.

Like the others said, I would assign those to a "waiting for" context. Note that you can put the entire context on hold so the actions don't show up as available actions in your next actions lists. Then when the pump house is built, you go and manually change the context from "waiting for" to whatever the context of the action really is. Unfortunately, this transition isn't automatic, but it does preserve the correct dependency structure. You can set up a perspective to look for "stalled" projects (projects with no available next action) and flip to this perspective daily to catch any of those "waiting for" tasks that become doable.