MATLAB: Can I force Matlab to wait ’til it finishes one command to run another

SimBiologytimerwait

I have a script that loads a SimBiology model using the simbiology() command. Then I try to get a handle for the model
simbiology('mymodel.sbproj');    % There are reasons why I use simbiology and not sbioloadproject
sbr = sbioroot;
mdls = sbr.models;
nmdls = numel(mdls);
mc = mdls(nmdls);
The problem is when I first try to get mdls. I get an empty array. Apparently, the model is still loading when the sbr=sbioroot and mdls = sbr.models commands run.
In windows command line files, you can use
START /WAIT myprogram.exe
to force myprogram.exe to finish running before going on the next line. Is there a similar artifice in Matab/Simbiology? Something like
finish('simbiology('mymodel.sbproj')'  ;
% or 

whilerunning
    simbiology('mymodel.sbproj');
end
I keep thinking that there's an easy way that I've forgotten…
The above is a general case. Of course, if simbiology() were re-written to return the model handle, and when the handle was requested, would not allow the script to proceed until the model was loaded, it would be great. Logical, too, because generally when you're loading a model you want to do something with that model before proceeding.
mc = simbiology('mymodel.sbproj');   % This solves the specific problem!
% or 
mc = simbiology('mymodel.sbproj','WaitToComplete');   % or this

Best Answer

Hi Jim,
The previous responses are correct: The simbiology command returns before the desktop completely loads the project, because the desktop is operating on different threads. So, welcome to the world of multi-threaded / parallel / asynchronous / <insert buzzword> complexity! Believe me, it makes life harder for SimBiology's developers, too. But hopefully you're mostly seeing the benefits of us living in that complexity and hiding it from you as much as possible.
Right now, there's one-line command that does what you want, but I'll suggest a workaround below. But thinking longer term, we hope to eliminate the need to open a project in the desktop just to preserve the diagram. If you can think of other reasons why it's important to know when a project is fully loaded, let us know so we can address those workflows, too.
Anyway, if all you care about is whether the model is accessible from the MATLAB command prompt (and not whether the desktop has completely finished loading the project), I came up with a solution (pasted below) that uses timer objects to periodically check whether the models have been loaded.
Here's the function. It takes the name of a project, the name of a variable to assign models to in the base workspace, and an optional callback that you can use to execute tasks that take the models as input arguments. So here's an example usage that simulates the Lotka demo project as soon as it's loaded (assigning the result to the base workspace variable sd): simbiologyNotify('lotka.sbproj', 'models', @(m) assignin('base', 'sd', sbiosimulate(m))) 
function simbiologyNotify(projectName, varName, callback)
if ~exist('callback', 'var')
    callback = @(models) [];
end
root = sbioroot;
oldModels = root.Models;
t = timer('ExecutionMode', 'fixedSpacing');
t.TimerFcn = @(t,e) timerFcn(t, root, oldModels, varName, callback);
simbiology(projectName);
start(t);
end
function timerFcn(t, root, oldModels, varName, callback)
models = setdiff(root.Models, oldModels);
if isempty(models)
    return
end
beep
fprintf('Models have been loaded. Assigning to base workspace variable "%s".\n', varName);
assignin('base', varName, models);
stop(t);
delete(t);
callback(models);
end
Note that you can't directly call this function from a script or function. If you do, you'll block the MATLAB interpreter, and that will prevent the desktop from loading the project. So you have to start thinking about asynchronous tasks the way we developers do: as a series of callback functions that get called as soon as their preconditions are met.
And one last note: If you really need to know whether the desktop has fully loaded the project into the GUI, I'll see if there's a way to get that information.
-Arthur
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