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6. eval() evaluates the passed string as a Python expression and returns the result. For example, eval("1 + 1") interprets and executes the expression "1 + 1" and returns the result (2). One reason you might be confused is because the code you cited involves a level of indirection.
Nov 16, 2017 · compile (string, '', 'eval') returns the code object that would have been executed had you done eval (string). Note that you cannot use statements in this mode; only a (single) expression is valid. compile (string, '', 'exec') returns the code object that would have been executed had you done exec (string).
ast.literal_eval raises an exception if the input isn't a valid Python datatype, so the code won't be executed if it's not. Use ast.literal_eval whenever you need eval . You shouldn't usually evaluate literal Python statements.
Yes, using eval is a bad practice. Just to name a few reasons: There is almost always a better way to do it. Very dangerous and insecure. Makes debugging difficult. Slow. In your case you can use setattr instead: class Song: """The class to store the details of each song""".
By the way, there are many ways to avoid using exec/eval if all you need is a dynamic name to assign, e.g. you could use a dictionary, the setattr function, or the locals() dictionary: >>> locals()['y'] = 1 >>> y 1
Jun 25, 2015 · 27. eval() only allows for expressions. Assignment is not an expression but a statement; you'd have to use exec instead. Even then you could use the globals() dictionary to add names to the global namespace and you'd not need to use any arbitrary expression execution. You really don't want to do this, you need to keep data out of your variable ...
try: eval (expr) except (SyntaxError, NameError, TypeError, ZeroDivisionError): pass Actually, virtually all existing exceptions can be thrown and any havoc can be wreaked by the evaluation of any code unless you fence out functions (e.g. os.system ("rm -rf /") , see also Eval really is dangerous ).
Nov 22, 2014 · 61. eval() will allow malicious data to compromise your entire system, kill your cat, eat your dog and make love to your wife. There was recently a thread about how to do this kind of thing safely on the python-dev list, and the conclusions were: It's really hard to do this properly.
eval() is used to verify an expression. On number is considered an expression, except octal numbers (numbers that start with 0). int() handles string to integer conversion. There are many reasons why you should avoid using eval(). Just keep in mind: Python 2.x. x = raw_input('Enter number here: ') Python 3.x.
393. model.eval() is a kind of switch for some specific layers/parts of the model that behave differently during training and inference (evaluating) time. For example, Dropouts Layers, BatchNorm Layers etc. You need to turn them off during model evaluation, and .eval() will do it for you. In addition, the common practice for evaluating ...
