casimport/README.md

casimport
=========

This is a python module that is designed to load Python code from a
cryptographic hash.  The idea is that instead of having to package
up simple code as a Python package, you can import it directly via
the hash.

There is the concept of aliases to make the import statements easier
to read.  An alias file is currently limited to python packages (modules
in a directory w/ an __init__.py file).  An example is the randpkg in
the fixtures directory.  You can put a file named cas_aliases.txt along
side the __init__.py file.  Each line of the file is:
```
<alias>	<url>
```

Where alias is a simple name, and url is a location to find the file
at.  Currently, at least one hash url must be specified.

The following url schemes are supported:
<dl>
<dt>hash</dt>
<dd>At least one of these MUST be specified. The url format is specified
by [hash-uri](https://github.com/hash-uri/hash-uri) and currently only
a hash value of sha256 is supported.</dd>
<dt>ipfs</dt>
<dd>The format follows ipfs scheme url as specified by the
[IPFS Addressing](https://github.com/ipfs/in-web-browsers/blob/master/ADDRESSING.md)
document.  It is recommend that CIDv1 addresses are used, as the
host portion of a URL is case insensitive, and CIDv0 (the current
default) values are case sensitive.  An example is:
`ipfs://bafkreibtbcckul7lwxqz7nyzj3dknhwrdxj5o4jc6gsroxxjhzz46albym`.</dd>
<dt>https</dt>
<dd>This is the standard web url that everyone is familar with.</dd>
</dl>

Usage
-----

Top level usage:
```
import casimport
from cas.v1_f_330884aa2febb5e19fb7194ec6a69ed11dd3d77122f1a5175ee93e73cf0161c3 import hello

print(repr(hello('Alice')))
```

Defintion of module names in cas package:
v<num>_<type>_<arg>

Currently v1 is defined, and has the following types:
	f	The arg is the hash of the Python source file.
		Example generated via: shasum -a 256 hello.py
	a	An alias.  Any aliases must be loaded before being
		processed.  This is a short name that could be used.

Configuration
-------------

By default, a configuration file is read from `~/.casimport/casimport.conf`.
The configuration file allows the specification of the priority of the
different modules (does casimport search IPFS or HTTPS urls first), and
the configuration each of the modules.

The first time you import casimport, a sample configuration will be created.
The default is a local cache the home directory, and then to use IPFS
gateway, followed by normal https urls.