Jip FAQ

Contents

• Jip FAQ
  • API related questions
    • How can I define and use a tool?
    • How can I access the tool options?
    • How can I access local variables within a pipeline?

API related questions

How can I define and use a tool?

Have a look at the following code:

>>> from jip import *
>>> @tool()
... def nop():
...    return ""
>>>

this defines a tool called nop, by default the function name is used, you can drop one in the @tool decorator.

The pipeline run() function takes a string or a tool instance. The string is used as tool name and a search is performed.

In this example, this would be enough to get the tool and run it:

>>> from jip import *
>>> p = Pipeline()
>>> p.run('nop')
nop

The run() method returns a Node object and also exposes all the properties of the node including its options.

How can I access the tool options?

Following the example before we can get a Node object from a pipeline and assign options to it:

>>> p = Pipeline()
>>> n = p.bash('cat ${input}')
>>> n.input = "Makefile"
>>> n.output = "out.txt"

The node has a set() function as a fall-back if direct assignment does not work, for example, if your option name conflicts with a function name of the Node object. In that case the Node functions are preferred.

You can always access the tool options using the self.args and self.options properties. The args dict contains the raw values while the options dict returns an instance of Option.

If you want to establish dependencies between tools in a pipeline, you have to use options but if you just want to access values args is fine.

Note

Note that options contain the raw values and are able to render them. The rendering is performed at the latest time possible though.

How can I access local variables within a pipeline?

Rendering values with access to the local context is done explicitly for JIP scripts. If you want to access the local context in Python you need to pass the locals() to the pipeline.

For example:

>>> p = jip.Pipeline()
>>> a = "Makefile"
>>> p.bash("wc -l ${a}")
bash
>>> b = jip.create_jobs(p)[0]
>>> assert b is not None
>>> assert b.command == '(wc -l ${a})'
>>>

Note that the nodes cmd option references “a”, a local variable. To resolve local variables you should drop the locals() into the pipeline context function before you return the pipeline or do anything with it:

>>> p = jip.Pipeline()
>>> a = "Makefile"
>>> p.bash("wc -l ${a}")
bash
>>> p.context(locals())
>>> b = jip.create_jobs(p)[0]
>>> assert b is not None
>>> print b.command
(wc -l Makefile)
>>> assert str(b.command) == '(wc -l Makefile)', b.command + "haha"