# vim:ts=4:sw=4:sts=4:et # -*- coding: utf-8 -*- """ Configuration framework for igraph. igraph has some parameters which usually affect the behaviour of many functions. This module provides the framework for altering and querying igraph parameters as well as saving them to and retrieving them from disk. """ import os.path from configparser import ConfigParser class Configuration: """Class representing igraph configuration details. Note that there is one primary instance of this class, which is used by igraph itself to retrieve configuration parameters when needed. You can access this instance with the L{instance()} method. You I{may} construct other instances by invoking the constructor directly, but these instances will I{not} affect igraph's behaviour. If you are interested in configuring igraph, use L{igraph.config} to get hold of the singleton instance and then modify it. General ideas ============= The configuration of igraph is stored in the form of name-value pairs. This object provides an interface to the configuration data using the syntax known from dict: >>> c = Configuration() >>> c["general.verbose"] = True >>> print(c["general.verbose"]) True Configuration keys are organized into sections, and the name to be used for a given key is always in the form C{section.keyname}, like C{general.verbose} in the example above. In that case, C{general} is the name of the configuration section, and C{verbose} is the name of the key. If the name of the section is omitted, it defaults to C{general}, so C{general.verbose} can be referred to as C{verbose}: >>> c = Configuration() >>> c["verbose"] = True >>> print(c["general.verbose"]) True User-level configuration is stored in C{~/.igraphrc} per default on Linux and Mac OS X systems, or in C{C:\\Documents and Settings\\username\\.igraphrc} on Windows systems. However, this configuration is read only when C{igraph} is launched through its shell interface defined in L{igraph.app.shell}. This behaviour might change before version 1.0. Known configuration keys ======================== The known configuration keys are presented below, sorted by section. When referring to them in program code, don't forget to add the section name, expect in the case of section C{general}. General settings ---------------- These settings are all stored in section C{general}. - B{shells}: the list of preferred Python shells to be used with the command-line C{igraph} script. The shells in the list are tried one by one until any of them is found on the system. C{igraph} functions are then imported into the main namespace of the shell and the shell is launched. Known shells and their respective class names to be used can be found in L{igraph.app.shell}. Example: C{IPythonShell, ClassicPythonShell}. This is the default, by the way. - B{verbose}: whether L{igraph} should talk more than really necessary. For instance, if set to C{True}, some functions display progress bars. Plotting settings ----------------- These settings specify the default values used by plotting functions. They are all stored in section C{plotting}. - B{backend}: either "cairo" if you want to use Cairo for plotting or "matplotlib" if you want to use the Matplotlib plotting backend. - B{layout}: default graph layout algorithm to be used. - B{mark_groups}: whether to mark the clusters by polygons when plotting a clustering object. - B{palette}: default palette to be used for converting integer numbers to colors. See L{colors.Palette} for more information. Valid palette names are stored in C{colors.palettes}. - B{wrap_labels}: whether to try to wrap the labels of the vertices automatically if they don't fit within the vertex. Default: C{False}. Shell settings -------------- These settings specify options for external environments in which igraph is embedded (e.g., IPython and its Qt console). These settings are stored in section C{shell}. - B{ipython.inlining.Plot}: whether to show instances of the L{Plot} class inline in IPython's console if the console supports it. Default: C{True} """ class Types: """Static class for the implementation of custom getter/setter functions for configuration keys""" def __init__(self): pass @staticmethod def setboolean(obj, section, key, value): """Sets a boolean value in the given configuration object. @param obj: a configuration object @param section: the section of the value to be set @param key: the key of the value to be set @param value: the value itself. C{0}, C{false}, C{no} and C{off} means false, C{1}, C{true}, C{yes} and C{on} means true, everything else results in a C{ValueError} being thrown. Values are case insensitive """ value = str(value).lower() if value in ("0", "false", "no", "off"): value = "false" elif value in ("1", "true", "yes", "on"): value = "true" else: raise ValueError("value cannot be coerced to boolean type") obj.set(section, key, value) @staticmethod def setint(obj, section, key, value): """Sets an integer value in the given configuration object. @param obj: a configuration object @param section: the section of the value to be set @param key: the key of the value to be set @param value: the value itself. """ obj.set(section, key, str(int(value))) @staticmethod def setfloat(obj, section, key, value): """Sets a float value in the given configuration object. Note that float values are converted to strings in the configuration object, which may lead to some precision loss. @param obj: a configuration object @param section: the section of the value to be set @param key: the key of the value to be set @param value: the value itself. """ obj.set(section, key, str(float(value))) _types = { "boolean": {"getter": ConfigParser.getboolean, "setter": Types.setboolean}, "int": {"getter": ConfigParser.getint, "setter": Types.setint}, "float": {"getter": ConfigParser.getfloat, "setter": Types.setfloat}, } _sections = ("general", "apps", "plotting", "remote", "shell") _definitions = { "general.shells": {"default": "IPythonShell,ClassicPythonShell"}, "general.verbose": {"default": True, "type": "boolean"}, "plotting.backend": {"default": "cairo"}, "plotting.layout": {"default": "auto"}, "plotting.mark_groups": {"default": False, "type": "boolean"}, "plotting.palette": {"default": "gray"}, "plotting.wrap_labels": {"default": False, "type": "boolean"}, "shell.ipython.inlining.Plot": {"default": True, "type": "boolean"}, } # The singleton instance we are using throughout other modules _instance = None def __init__(self, filename=None): """Creates a new configuration instance. @param filename: file or file pointer to be read. Can be omitted. """ self._config = ConfigParser() self._filename = None # Create default sections for sec in self._sections: self._config.add_section(sec) # Create default values for name, definition in self._definitions.items(): if "default" in definition: self[name] = definition["default"] if filename is not None: self.load(filename) @property def filename(self): """Returns the filename associated to the object. It is usually the name of the configuration file that was used when creating the object. L{Configuration.load} always overwrites it with the filename given to it. If C{None}, the configuration was either created from scratch or it was updated from a stream without name information.""" return self._filename def _get(self, section, key): """Internal function that returns the value of a given key in a given section.""" definition = self._definitions.get("%s.%s" % (section, key), {}) getter = None if "type" in definition: getter = self._types[definition["type"]].get("getter") if getter is None: getter = self._config.__class__.get return getter(self._config, section, key) @staticmethod def _item_to_section_key(item): """Converts an item description to a section-key pair. @param item: the item to be converted @return: if C{item} contains a period (C{.}), it is splitted into two parts at the first period, then the two parts are returned, so the part before the period is the section. If C{item} does not contain a period, the section is assumed to be C{general}, and the second part of the returned pair contains C{item} unchanged""" if "." in item: section, key = item.split(".", 1) else: section, key = "general", item return section, key def __contains__(self, item): """Checks whether the given configuration item is set. @param item: the configuration key to check. @return: C{True} if the key has an associated value, C{False} otherwise. """ section, key = self._item_to_section_key(item) return self._config.has_option(section, key) def __getitem__(self, item): """Returns the given configuration item. @param item: the configuration key to retrieve. @return: the configuration value""" section, key = self._item_to_section_key(item) if key == "*": # Special case: retrieving all the keys within a section and # returning it in a dict keys = self._config.items(section) return dict((key, self._get(section, key)) for key, _ in keys) else: return self._get(section, key) def __setitem__(self, item, value): """Sets the given configuration item. @param item: the configuration key to set @param value: the new value of the configuration key """ section, key = self._item_to_section_key(item) definition = self._definitions.get("%s.%s" % (section, key), {}) setter = None if "type" in definition: setter = self._types[definition["type"]].get("setter", None) if setter is None: setter = self._config.__class__.set return setter(self._config, section, key, value) def __delitem__(self, item): """Deletes the given item from the configuration. If the item has a default value, the default value is written back instead of the current value. Without a default value, the item is really deleted. """ section, key = self._item_to_section_key(item) definition = self._definitions.get("%s.%s" % (section, key), {}) if "default" in definition: self[item] = definition["default"] else: self._config.remove_option(section, key) def has_key(self, item): """Checks if the configuration has a given key. @param item: the key being sought""" if "." in item: section, key = item.split(".", 1) else: section, key = "general", item return self._config.has_option(section, key) def load(self, stream=None): """Loads the configuration from the given file. @param stream: name of a file or a file object. The configuration will be loaded from here. Can be omitted, in this case, the user-level configuration is loaded. """ stream = stream or get_user_config_file() if isinstance(stream, str): stream = open(stream, "r") file_was_open = True self._config.read_file(stream) self._filename = getattr(stream, "name", None) if file_was_open: stream.close() def save(self, stream=None): """Saves the configuration. @param stream: name of a file or a file object. The configuration will be saved there. Can be omitted, in this case, the user-level configuration file will be overwritten. """ stream = stream or get_user_config_file() if not hasattr(stream, "write") or not hasattr(stream, "close"): stream = open(stream, "w") file_was_open = True self._config.write(stream) if file_was_open: stream.close() @classmethod def instance(cls): """Returns the single instance of the configuration object.""" if cls._instance is None: cfile = get_user_config_file() try: config = cls(cfile) except IOError: # No config file yet, whatever config = cls() cls._instance = config return cls._instance def get_user_config_file(): """Returns the path where the user-level configuration file is stored""" return os.path.expanduser("~/.igraphrc") def init(): """Default mechanism to initiate igraph configuration This method loads the user-specific configuration file from the user's home directory, or if it does not exist, creates a default configuration. The method is safe to be called multiple times, it will not parse the configuration file twice. @return: the L{Configuration} object loaded or created.""" return Configuration.instance()