Relax source design

The following is a set of notes which will be used to design the layout of functions, modules, and packages in relax.

General

The check_*() functions

These functions are for performing checks for certain data being present. They can return True or False, throw RelaxWarnings, or raise RelaxErrors.

Packages

These functions are found in the pipe_control and specific_analyses packages:

• pipe_control: The check_*() functions are located in the individual modules of this package.
• specific_analyses: For these packages, a special 'checks' module should be created for these functions.

Design

The check_*() functions should have the 'escalate' keyword argument which can have the following values:

• 0 - This will simply cause the function to return True or False.
• 1 - In addition to returning True or False, the function will throw a RelaxWarning for better user feedback.
• 2 - This will cause a RelaxError to be raised if the data is missing, not set up, etc. Otherwise the function returns True.

Implementation

Here is a prototype function:

def check_xxx(escalate=0):
    """Check if xxx.

    @keyword escalate:      The feedback to give if the check fails.  This can be 0 for no printouts, 1 to throw a RelaxWarning, or 2 to raise a RelaxError.
    @type escalate:         int
    @raises RelaxError:     If escalate is set to 2 and the check fails.
    @return:                True if the check passes, False otherwise.
    @rtype:                 bool
    """

    # Init.
    flag = True
    msg = ''

    # Check that...
    if not something():
        flag = False
        msg = "Something is missing."

    # Warnings and errors.
    if not flag and escalate == 1:
        warn(RelaxWarning(msg))
    elif not flag and escalate == 2:
        raise RelaxError(msg)

    # Return the answer.
    return flag