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# encoding: utf-8
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"""
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Utilities for working with stack frames.
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"""
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#-----------------------------------------------------------------------------
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# Copyright (C) 2008-2011 The IPython Development Team
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#
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# Distributed under the terms of the BSD License. The full license is in
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# the file COPYING, distributed as part of this software.
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#-----------------------------------------------------------------------------
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#-----------------------------------------------------------------------------
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# Imports
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#-----------------------------------------------------------------------------
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import sys
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#-----------------------------------------------------------------------------
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# Code
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#-----------------------------------------------------------------------------
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def extract_vars(*names,**kw):
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"""Extract a set of variables by name from another frame.
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Parameters
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----------
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*names : str
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One or more variable names which will be extracted from the caller's
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frame.
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**kw : integer, optional
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How many frames in the stack to walk when looking for your variables.
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The default is 0, which will use the frame where the call was made.
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Examples
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--------
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::
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In [2]: def func(x):
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...: y = 1
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...: print(sorted(extract_vars('x','y').items()))
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...:
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In [3]: func('hello')
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[('x', 'hello'), ('y', 1)]
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"""
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depth = kw.get('depth',0)
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callerNS = sys._getframe(depth+1).f_locals
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return dict((k,callerNS[k]) for k in names)
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def extract_vars_above(*names):
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"""Extract a set of variables by name from another frame.
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Similar to extractVars(), but with a specified depth of 1, so that names
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are extracted exactly from above the caller.
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This is simply a convenience function so that the very common case (for us)
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of skipping exactly 1 frame doesn't have to construct a special dict for
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keyword passing."""
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callerNS = sys._getframe(2).f_locals
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return dict((k,callerNS[k]) for k in names)
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def debugx(expr,pre_msg=''):
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"""Print the value of an expression from the caller's frame.
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Takes an expression, evaluates it in the caller's frame and prints both
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the given expression and the resulting value (as well as a debug mark
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indicating the name of the calling function. The input must be of a form
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suitable for eval().
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An optional message can be passed, which will be prepended to the printed
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expr->value pair."""
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cf = sys._getframe(1)
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print('[DBG:%s] %s%s -> %r' % (cf.f_code.co_name,pre_msg,expr,
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eval(expr,cf.f_globals,cf.f_locals)))
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# deactivate it by uncommenting the following line, which makes it a no-op
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#def debugx(expr,pre_msg=''): pass
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def extract_module_locals(depth=0):
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"""Returns (module, locals) of the function `depth` frames away from the caller"""
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f = sys._getframe(depth + 1)
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global_ns = f.f_globals
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module = sys.modules[global_ns['__name__']]
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return (module, f.f_locals)
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