feature-check - query a program for supported features

The feature_check library obtains the list of supported features from a program via various methods and allows programs to check for the presence and, possibly, versions of specific features.

The feature_check library is fully typed.

Obtaining the features supported by a program

The obtain_features() function in the feature_check module runs a program with the appropriate option to obtain its list of features; the default is to pass the --features option, but this may be overridden. The obtain_features() function then examines the output to find a line that matches the specified prefix (or the default Features: prefix) and expects the rest of the line to be a whitespace-separated list of either feature names or name=version pairs. It returns a dictionary of the features obtained with their versions (or 1.0 if only a feature name was found in the program's output).

import feature_check

data = feature_check.obtain_features("timelimit")
print(data.get("subsecond", "not supported"))

For programs that need a different command-line option to list features:

import feature_check

print("SSL" in feature_check.obtain_features("curl", option="--version"))

Testing for feature versions

The feature_check library also provides a simple expression evaluation mechanism for examining feature versions - the expr module defines several Expr and Result classes and also provides the parse_simple() function (also exported by feature_check() itself) for creating simple version comparisons:

import feature_check

data = feature_check.obtain_features("timelimit")
expr = feature_check.parse_simple("subsecond >= 1")
print(expr.evaluate(data).value)

Contact the author

For more information, please see the feature_check library's homepage or contact the author, Peter Pentchev.