1

"""

     2

    Friendly wrapper around the rrdtool python interface

     3

"""

     4

    11

def normalize_option_key (key) :

    12

    """

    13

        Normalize the given option key.

    14

    15

        A -- is prepended, and _'s are converted to -

    16

    """

    17

    18

    return '--' + str(key).replace('_', '-')

    19

    20

def normalize_option_multi (key, values) :

    21

    """

    22

        Normalize a list of option values, returning a series of --opt, val1, --opt, val2, ...

    23

    """

    24

    25

    for value in values :

    26

        yield key

    27

        yield str(value)

    28

    29

def normalize_option (key, value) :

    30

    """

    31

        Normalize the given option to a series of cmd-args.

    32

    33

        If value is None or False, no cmd-args are emitted. If value is True, only --opt is emitted. If value is a list,

    34

        --opt and value are emitted for each item.

    35

    36

        Otherwise, both --opt and str(value) are emitted.

    37

    """

    38

    39

    key = normalize_option_key(key)

    40

    41

    if value is None or value is False :

    42

        # omit

    43

        return ()

    44

    45

    elif value is True :

    46

        # flag

    47

        return (key, )

    48

    49

    elif isinstance(value, list) :

    50

        # list of option values

    52

    53

    else :

    54

        # option value

    55

        return (key, str(value))

    56

    57

def merge_opts (*all_opts) :

    58

    """

    59

        Merge the given series of opt dicts

    60

    """

    61

    62

    out = dict()

    63

    64

    for opts in all_opts :

    65

        # XXX: not strictly true, merge lists

    66

        out.update(opts)

    67

    68

    return out

    69

    70

def run_cmd (func, pre_args, opts, post_args) :

    71

    """

    72

        Run the given rrdtool.* function, formatting the given positional arguments and options.

    73

    """

    74

    76

    opt_items = (normalize_option(key, value) for key, value in opts.iteritems())

    77

    79

    opt_args = [item for items in opt_items for item in items]

    80

    81

    # positional arguments

    82

    pre_args = [str(arg) for arg in pre_args]

    83

    post_args = [str(arg) for arg in post_args]

    84

    85

    # full arguments

    89

    90

    return func(*args)

    91

    92

def graph (out_path, *args, **opts) :

   101

    return run_cmd(rrdtool.graph, (out_path, ), opts, args)

   102