Re: How to check the exists of a name?
David 71da...@libero.it (D) wrote: D Il Sat, 17 Oct 2009 23:43:36 -0700 (PDT), StarWing ha scritto: I got a idea, use a try...except statement. there are another way to do it ? (I just curious now, because I solve my problem in another way :-) D locals().has_key(myname) D globals().has_key(myname) 1. This excludes builtins. The OP says: `no matter where is it', so that suggests also builins. 2. The more modern invocation would be myname in locals() or myname in globals(). In Python3 the other one isn't supported anymore. -- Piet van Oostrum p...@vanoostrum.org WWW: http://pietvanoostrum.com/ PGP key: [8DAE142BE17999C4] -- http://mail.python.org/mailman/listinfo/python-list
How to check the exists of a name?
Sometimes I want to make a simple flags. and i need to check there is a name in current scope or not (that is, we can visit this name, no matter where is it). and how to do that in python? -- http://mail.python.org/mailman/listinfo/python-list
Re: How to check the exists of a name?
On Sat, Oct 17, 2009 at 11:30 PM, StarWing weasley...@sina.com wrote: Sometimes I want to make a simple flags. and i need to check there is a name in current scope or not (that is, we can visit this name, no matter where is it). and how to do that in python? You should avoid needing to do that in the first place. Common alternatives include using a dict instead of variables, depending on your circumstances. Cheers, Chris -- http://blog.rebertia.com -- http://mail.python.org/mailman/listinfo/python-list
Re: How to check the exists of a name?
Il Sat, 17 Oct 2009 23:30:02 -0700 (PDT), StarWing ha scritto: Sometimes I want to make a simple flags. and i need to check there is a name in current scope or not (that is, we can visit this name, no matter where is it). and how to do that in python? Just use it in a try..except block. try: print myname except NameError: print myname does not exists D. -- http://mail.python.org/mailman/listinfo/python-list
Re: How to check the exists of a name?
On 10月18日, 下午2时37分, Chris Rebert c...@rebertia.com wrote: On Sat, Oct 17, 2009 at 11:30 PM, StarWing weasley...@sina.com wrote: Sometimes I want to make a simple flags. and i need to check there is a name in current scope or not (that is, we can visit this name, no matter where is it). and how to do that in python? You should avoid needing to do that in the first place. Common alternatives include using a dict instead of variables, depending on your circumstances. Cheers, Chris --http://blog.rebertia.com Okay... Thank you... But if I want to do that, what shall I do? I got a idea, use a try...except statement. there are another way to do it ? (I just curious now, because I solve my problem in another way :-) -- http://mail.python.org/mailman/listinfo/python-list
Re: How to check the exists of a name?
Il Sat, 17 Oct 2009 23:43:36 -0700 (PDT), StarWing ha scritto: I got a idea, use a try...except statement. there are another way to do it ? (I just curious now, because I solve my problem in another way :-) locals().has_key(myname) globals().has_key(myname) D. -- http://mail.python.org/mailman/listinfo/python-list
Re: How to check the exists of a name?
On Sat, Oct 17, 2009 at 11:43 PM, StarWing weasley...@sina.com wrote: On 10月18日, 下午2时37分, Chris Rebert c...@rebertia.com wrote: On Sat, Oct 17, 2009 at 11:30 PM, StarWing weasley...@sina.com wrote: Sometimes I want to make a simple flags. and i need to check there is a name in current scope or not (that is, we can visit this name, no matter where is it). and how to do that in python? You should avoid needing to do that in the first place. Common alternatives include using a dict instead of variables, depending on your circumstances. Okay... Thank you... But if I want to do that, what shall I do? I got a idea, use a try...except statement. there are another way to do it ? (I just curious now, because I solve my problem in another way :-) Perhaps if you could explain why there's the possibility these variables might not be defined... Cheers, Chris -- http://blog.rebertia.com -- http://mail.python.org/mailman/listinfo/python-list
Re: How to check the exists of a name?
David 71da...@libero.it writes: Il Sat, 17 Oct 2009 23:43:36 -0700 (PDT), StarWing ha scritto: I got a idea, use a try...except statement. there are another way to do it ? (I just curious now, because I solve my problem in another way :-) locals().has_key(myname) globals().has_key(myname) The ‘dict.has_key’ method is deprecated, and is removed in Python 3. The ‘in’ operator now works on dict objects: 'foo' in locals() 'foo' in globals() -- \ “We must become the change we want to see.” —Mahatma Gandhi | `\ | _o__) | Ben Finney -- http://mail.python.org/mailman/listinfo/python-list
Re: How to check the exists of a name?
On Sat, 17 Oct 2009 23:30:02 -0700, StarWing wrote: Sometimes I want to make a simple flags. and i need to check there is a name in current scope or not (that is, we can visit this name, no matter where is it). and how to do that in python? (1) Use a sentinel: myname = None # always exists ... # much later if myname is None: print initialising myname else: process(myname) (2) Try it and see: try: myname except NameError: print myname does not exist else: print myname exists (3) Look Before You Leap: # inside a class: 'myname' in self.__dict__ or self.__class__.__dict__ # better, because it uses inheritance and supports __slots__: hasattr(self, 'myname') # inside a function 'myname' in locals() 'myname' in globals() -- Steven -- http://mail.python.org/mailman/listinfo/python-list
Re: How to check the exists of a name?
On Sat, 17 Oct 2009 23:54:37 -0700, Chris Rebert wrote: Perhaps if you could explain why there's the possibility these variables might not be defined... If I have to support older versions of Python: try: bin except NameError: # Define my own. def bin(arg): ... But for my own variables? No way. I just make sure they're defined. -- Steven -- http://mail.python.org/mailman/listinfo/python-list
