Global DRMS-module structure representing the default command-line arguments for a DRMS module.

module_args, a global array of ModuleArgs_t structures, provides a standard mechanism for declaring the parameters expected by a module along with their types and default values, if any. module_args must be declared in every module. The elements of the module_args array are parsed and used by the cmdparams library to populate the global CmdParams_t structure, which provides access to cmd-line arguments (please see cmdparams_parse for more information about how the cmdparams library uses module_args).

The module_args array must contain at least one element, which must be of type ARG_END. Any array elements following the ARG_END element are ignored. Each element has five fields: type, name, (default) value, description, and range. The value field contains the actual default value for the argument should the argument be ommitted from the cmd-line. All fields are strings, and the type field is required to not be NULL. The description field, which provides a terse summary of the purpose of the argument, is always optional. But the disposition of the name, value, and range fields depends on the type of argument (see the table below; for example, for the ARG_FLAG, the value field is not used, but for ARG_INT, that field is used).

If applicable, the default value and range are specified as strings in the module_args array. And they are stored in the CmdParams_t structure as strings. But by specifying a type, such as ARG_INT, this declares that the module intends to interpret the the string as a specific data type (such as an int). However, it is important to note that there is NOTHING to prevent the module from interpreting the stored string as any type it desires. The module's code performs this interpretation when it uses one of the cmdparams_get_XXX() functions - the type in the name of the function will cause the stored string to be interpreted as a definite data type. For example, if a type of ARG_INT is specified, the module should call cmdparams_get_int(), but not cmdparams_get_time() to obtain and interpret the value.

The following table summarizes the various ModuleArgs_t argument types, providing guidelines for their specification in the global module_args array and their use in on the cmd-line:

Arg Type required fields optional fields Description
ARG_INT type, name value, range, description The cmd-line argument is to be interpreted by the module as type int. If the value field is present, it must contain an ascii string that can be converted to an integer. If the value field is missing or if the field is the empty string, then the cmd-line argument must be present. The range field is optional. If present, it must contain an ascii string that specifies a range of real numbers (see cmdparams_parse).
ARG_FLOAT type, name value, range, description The cmd-line argument is to be interpreted by the module as type float. If the value field is present, it must contain an ascii string that can be converted to a float. If the value field is missing or if the field is the empty string, then the cmd-line argument must be present. The range field is optional. If present, it must contain an ascii string that specifies a range of real numbers (see cmdparams_parse).
ARG_DOUBLE type, name value, range, description The cmd-line argument is to be interpreted by the module as type double. If the value field is present, it must contain an ascii string that can be converted to a double. If the value field is missing or if the field is the empty string, then the cmd-line argument must be present. The range field is optional. If present, it must contain an ascii string that specifies a range of real numbers (see cmdparams_parse).
ARG_TIME type, name value, description The cmd-line argument is to be interpreted by the module as a time string (as defined in sscan_time). If the value field is present, it must contain an ascii time string. If the value field is missing or if the field is the empty string, then the cmd-line argument must be present.
ARG_STRING type, name value, description The cmd-line argument is to be interpreted by the module as a character string. If the value field is present, it must contain an ascii string. If the value field is missing or if the field is the empty string, then the cmd-line argument must be present.
ARG_FLAG type, name description The cmd-line argument is to be interpreted by the module as a binary flag. If the name of the flag argument contains a single character X, then to "set" the flag, provide "-X" on the cmd-line. If the name of the flag contains more than a single character "name", then provide "--name" on the cmd-line. Do not provide a default value, as cmdparams does not use the value field for flags. If the flag is not provided on the cmd-line the flag is by default not set.
ARG_NUME type, name, range value, description The cmd-line argument is to be interpreted by the module as the string representation of an enumeration id, as defined in the range field. If the value field is present, it must contain the string representation of an enumeration id. If the value field is missing or if the field is the empty string, then the cmd-line argument must be present. The range field contains a comma-separated list of enumeration ids (strings). The first item in the list is associated with an integer value of 0, and each subsequent member is associated with a value one greater than the previous id. The cmd-line argument must contain one of the member strings. See cmdparams_parse for more information.
ARG_INTS type, name value, description The cmd-line argument is to be interpreted by the module as a comma-separated list of integer values. If the value field is present, it must contain an ascii string that can be converted to one or more integers. If the value field is missing or if the field is the empty string, then the cmd-line argument must be present. See cmdparams_parse for more information.
ARG_FLOATS type, name value, description The cmd-line argument is to be interpreted by the module as a comma-separated list of floating point values. If the value field is present, it must contain an ascii string that can be converted to one or more integers. If the value field is missing or if the field is the empty string, then the cmd-line argument must be present. See cmdparams_parse for more information.
ARG_DOUBLE type, name value, description Synonymous with ARG_FLOATS
ARG_VOID ? none (not yet implemented - not clear what this type is for)
ARG_DATASERIES type, name value, description Currently synonymous with ARG_STRING (but reserved for use with dataseries names that can be used in a database query).
ARG_DATASET type, name value, description Currently synonymous with ARG_STRING (but reserved for use with dataseries/record filter names that can be used in a database query).
ARG_NEWDATA type, name value, description (not yet implemented - not clear what this type is for)
ARG_END type none Signals the end of the parsed argument list. Elements may follow in the array, but will be ignored.

Bug:
Range inspection does not currently extend to arguments of type ARG_INTS, ARG_FLOATS, and ARG_DOUBLES
See also:
module cmdparams.h sscan_time

Definition at line 656 of file jsoc_info.c.


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