with-statement

问题 What is a clean way to create a multi-line with in python? I want to open up several files inside a single with , but it's far enough to the right that I want it on multiple lines. Like this: class Dummy: def __enter__(self): pass def __exit__(self, type, value, traceback): pass with Dummy() as a, Dummy() as b, Dummy() as c: pass Unfortunately, that is a SyntaxError . So I tried this: with (Dummy() as a, Dummy() as b, Dummy() as c): pass Also a syntax error. However, this worked: with Dummy()

问题 Update 2 @G. Grothendieck posted two approaches. The second one is changing the function environment inside a function. This solves my problem of too many coding replicates. I am not sure if this is a good method to pass through the CRAN check when making my scripts into a package. I will update again when I have some conclusions. Update I am trying to pass a lot of input argument variables to f2 and do not want to index every variable inside the function as env$c, env$d, env$calls , that is

问题 Some code to illustrate my question: With Test.AnObject .Something = 1337 .AnotherThing = "Hello" ''// why can't I do this to pass the object itself: Test2.Subroutine(.) ''// ... and is there an equivalent, other than repeating the object in With? End With 回答1: There is no way to refer to the object referenced in the With statement, other than repeating the name of the object itself. EDIT If you really want to, you could modify your an object to return a reference to itself Public Function

问题 Am getting this error when using the pool.map(funct, iterable) : AttributeError: __exit__ No Explanation, only stack trace to the pool.py file within the module. using in this way: with Pool(processes=2) as pool: pool.map(myFunction, mylist) pool.map(myfunction2, mylist2) I suspect there could be a problem with the picklability (python needs to pickle , or transform list data into byte stream) yet I'm not sure if this is true or if it is how to debug. EDIT: new format of code that produces

问题 I been reading bad things about the with keyword in delphi but, in my opinion, if you don't over use it. It can make your code look simple. I often put all my TClientDataSets and TFields in TDataModules. So in my forms I had code like this procedure TMyForm.AddButtonClick(Sender: TObject); begin with LongNameDataModule do begin LongNameTable1.Insert; LongNameTable1_Field1.Value := "some value"; LongNameTable1_Field2.Value := LongNameTable2_LongNameField1.Value; LongNameTable1_Field3.Value :=

问题 How do I test the following code with mocks (using mocks, the patch decorator and sentinels provided by Michael Foord's Mock framework): def testme(filepath): with open(filepath, 'r') as f: return f.read() 回答1: The way to do this has changed in mock 0.7.0 which finally supports mocking the python protocol methods (magic methods), particularly using the MagicMock: http://www.voidspace.org.uk/python/mock/magicmock.html An example of mocking open as a context manager (from the examples page in

问题 With this code "VB.Net 2005" Dim dep as new Department With dep.AddNewEmployee() .FirstName = "Mr. A" .LastName = "B" If TypeOf {dep.AddNewEmployee()'s instance} is Serializable then 'Do something End If end With in {dep.AddNewEmployee()'s instance} is there any syntax for this code. Is it possible? 回答1: There is no way to do that by using the With syntax. You could just add a local variable that references the new object though: Dim dep as new Department Dim emp = dep.AddNewEmployee() With

问题 I am trying to come to grips with using with statements in delphi properly. Overall it seems fairly simple to do simple things with but I am interested in finding some good code examples and/or tutorials on using nested with statements. E.G. with object1, object2, etc... do begin statements end; What I am unsure of is the order of precedence when using with statements in such a manner. Any advice is appreciated. 回答1: The best advice I can give you is: Do not use with ever. If you feel like

问题 I have the following code which runs perfectly on Python 2.6.6: import tempfile with tempfile.NamedTemporaryFile() as scriptfile: scriptfile.write(<variablename>) scriptfile.flush() subprocess.call(['/bin/bash', scriptfile.name]) However, when I try to run it on Python 2.4.3, I get the following error: File "<stdin>", line 2 with tempfile.NamedTemporaryFile() as scriptfile ^ SyntaxError: invalid syntax Is there a change in syntax in Python 2.4.3? 回答1: Python 2.4 does not support the with

问题 I'm trying to use the python-daemon module. It supplies the daemon.DaemonContext class to properly daemonize a script. Although I'm primarily targeting Python 2.6+, I'd like to maintain backwards compatibility to version 2.4. Python 2.5 supports importing contexts from future , but Python 2.4 has no such facility. I figured I could just catch whatever error the with statement raises and enter and exit the context manually for 2.4, but I can't seem to catch the SyntaxError raised. Is there any