Add functions

[md5]

This patch adds the following functions:

• dict: creates a map from a list of pairs. facilitates passing data to subtemplates.
• sha1: creates a sha1 hex string from another string
• json: returns the JSON string representation of an object (cf. docker inspect)
• last: returns the last element of an array or slice or the last character in a string

[thaJeztah]

Thanks! Should there be some documentation added and possibly an example on how to make use of these?

[md5]

What fun would that be?

I didn't see a place in the docs that documents the current template functions, other than the de facto documentation in the examples. I suppose I could create an example or two. And now that I think about it, first would be nice...

[thaJeztah]

😄 yes documentation is quite lacking. If you're able to dabble down some stuff, would be great!

[md5]

I've added a "Templating" section to the README.md.

In the process of writing it, I came across Hugo and it made me want to add most of their functions as well: http://gohugo.io/templates/functions/

However, I'd like to see this merged as is; I can open another PR to add more functions if (when) I get around to needing them.

[thaJeztah]

Nice! And fully agreed, docs should not uphold merging of this PR (just my opinion)

Thanks a lot!

[jwilder]

This is failing to compile for me:

./template.go:15: imported and not used: "sort"

[md5]

Crap! I had run "go test" on this branch before pushing it, but then I decided to remove a half-ass implementation of "sort". I guess that dropping that commit wasn't enough...

[jwilder]

Thanks!

[thaJeztah]

👍

[md5]

Sweet!

My local branch has getenv and a couple other things that I'll be sending a PR for next week probably. I'm also still waiting for support for the TLS event stream to be merged in go-dockerclient, after which I can have a TLS PR for docker-gen.

At that point, it will be possible for everyone to use docker-gen on OS X like I've been doing :) (or with any TLS-enabled remote docker host for that matter)

[thaJeztah]

Sweet!