else/Syshub/syshub.py

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2015-08-26 11:38:43 +00:00
'''
This module allows the user to redirect sys.stdout, stdin, and exceptions
streams (referred to as std* collectively) on a per-module basis. That is,
a main program can import both moduleA and moduleB, then register them here
so that any print statements or prompts in the modules will behave differently.
'''
import inspect
import sys
import traceback
class SysRouter:
def __init__(self):
if self.__class__.ROUTER_EXISTS:
raise ValueError('You may only instantiate one of each SysRouter')
self.__class__.ROUTER_EXISTS = True
def router_get_caller(self, key, default, jumps=0):
stack = inspect.stack()
calling_frame = stack[2+jumps][0]
calling_module = inspect.getmodule(calling_frame)
if calling_module is None:
try:
calling_frame = stack[3+jumps][0]
calling_module = inspect.getmodule(calling_frame)
calling_name = calling_module.__name__
except:
calling_name = ''
else:
calling_name = calling_module.__name__
rerouted = SYSHUB_MAP.get(calling_name, {}).get(key, default)
return rerouted
class SysRouterOut(SysRouter):
ROUTER_EXISTS = False
def flush(self):
STDOUT.flush()
def write(self, data):
rerouted = self.router_get_caller('out', STDOUT.write)
return rerouted(data)
class SysRouterIn(SysRouter):
ROUTER_EXISTS = False
def readline(self):
rerouted = self.router_get_caller('in', STDIN.readline)
return rerouted()
#class SysRouterErr(SysRouter):
# ROUTER_EXISTS = False
#
# def flush(self):
# STDERR.flush()
#
# def write(self, data):
# rerouted = self.router_get_caller('out', STDERR.write)
# return rerouted(data)
class SysRouterExc(SysRouter):
ROUTER_EXISTS = False
def __call__(self, exception_type, exception_instance, trace):
caller = traceback._format_exception_iter(ValueError, exception_instance, trace,None, None)
caller = list(caller)[-2]
caller = caller.split('"')[1]
caller = caller.replace('\\', '/')
caller = caller.split('/')[-1]
caller = caller.split('.')[0]
rerouted = SYSHUB_MAP.get(caller, {}).get('exc', EXCEPTHOOK)
rerouted(exception_type, exception_instance, trace)
SYSHUB_MAP = {}
STDOUT = sys.stdout
STDIN = sys.stdin
#STDERR = sys.stderr
EXCEPTHOOK = sys.excepthook
sys.stdout = SysRouterOut()
sys.stdin = SysRouterIn()
#sys.stderr = SysRouterErr()
sys.excepthook = SysRouterExc()
def register(module, calltype, method):
'''
Register a module in the syshub map.
When the module performs an input, output, or err operation, Syshub will
check the map so see if it should redirect the call to the provided
method.
Registered modules will not affect the behavior of unregistered modules.
Rerouting a module's 'out' will not affect that module's 'in', etc.
-----
parameters:
module = the module object from which calls will be rerouted.
calltype = one of {'out', 'in', 'exc}, corresponding to sys.std*
and sys.excepthook
method = the method to which any arguments intended for the std* method
will be passed.
-----
SYSHUB_MAP is kept in the format:
{module: {'out': method, 'in': method, 'exc': method}}
'''
i = module.__name__
if i in SYSHUB_MAP:
SYSHUB_MAP[i][calltype] = method
else:
SYSHUB_MAP[i] = {calltype: method}