Coverage for local/lib/python2.7/site-packages/sage/misc/python.py : 78%

"Evaluating Python code without any preparsing" 

class Python: 

""" 

Allows for evaluating a chunk of code without any preparsing. 

""" 

def eval(self, x, globals, locals=None): 

r""" 

Evaluate x with given globals; locals is completely ignored. 

This is specifically meant for evaluating code blocks with 

``%python`` in the notebook. 

INPUT: 

x -- a string 

globals -- a dictionary 

locals -- completely IGNORED 

EXAMPLES:: 

sage: from sage.misc.python import Python 

sage: python = Python() 

sage: python.eval('2+2', globals()) 

4 

'' 

Any variables that are set during evaluation of the block 

will propagate to the globals dictionary. :: 

sage: python.eval('a=5\nb=7\na+b', globals()) 

12 

'' 

sage: b 

7 

The locals variable is ignored -- it is there only for 

completeness. It is ignored since otherwise the following 

will not work:: 

sage: python.eval("def foo():\n return 'foo'\nprint(foo())\ndef mumble():\n print('mumble {}'.format(foo()))\nmumble()", globals()) 

foo 

mumble foo 

'' 

sage: mumble 

<function mumble at ...> 

""" 

x = x.strip() 

y = x.split('\n') 

if len(y) == 0: 

return '' 

s = '\n'.join(y[:-1]) + '\n' 

t = y[-1] 

try: 

z = compile(t + '\n', '', 'single') 

except SyntaxError: 

s += '\n' + t 

z = None 

eval(compile(s, '', 'exec'), globals, globals) 

if not z is None: 

eval(z, globals) 

return '' 

python = Python()