Check if the program that runs the contract is actually available on the system

[Tom Beckmann]

You should check if the program that is running the contract is available on the system or, which would probably be simpler add an entry to the .contract file listing dependencies. Or you could restrict the installation of the contracts only to the programs (at the moment, I think, for example postler.contract is installed with contractor), but this last solution would make it harder to create "third-party" contracts for programs like gimp.

[Sergey "Shnatsel" Davidoff (shnatsel)]

I suggest using TryExec= key, like in .desktop files

[Sergey "Shnatsel" Davidoff (shnatsel)]

Info on TryExec= can be found here: http://standards.freedesktop.org/desktop-entry-spec/latest/ar01s05.html

This is needed for e.g. Inkscape contracts which work via BASH wrappers; while they're shipped with those wrappers, it depends on Inkscape's presence if they will work or not.

[Sergey "Shnatsel" Davidoff (shnatsel)]

For reference, Inkscape contracts can be found here: lp:~elementary-os/contractor/inkscape-contracts

[Sergey "Shnatsel" Davidoff (shnatsel)]

Ammonkey did commit a fix to Extended Actions, see http://bazaar.launchpad.net/~marlin-devs/extended-actions/trunk/revision/3 but his fix is not sufficient, won't work for Inkscape contracts for example.

[Danielle Foré (danrabbit)]

While a cool new feature, I don't think this is essential for Luna Beta. We shouldn't be shipping any contracts that don't have installed binaries.

[Cassidy James Blaede (cassidyjames)]

Discussion from the Google Doc (http://goo.gl/A2lHJ):

Сергей Давыдов
5:55 AM Jul 18
This is required because of dpkg limitations - there's no concept of "linking" packages and patching every package just to include a contract is not viable, so we have to ship bunches of contracts and then show only those which are actually available on the system.

This is also needed for contracts employing wrapper scripts because executability of the contract depends on the presence of the base app, not the wrapper script.

Not taking all that into account, it's basic must-have robustness.

Fabian Thoma
4:25 PM Oct 26
Agreed, should be done, that's why it's a bug that's Confirmed

[Victor Martinez (victored)]

We can do this by using TryExec