spawn problem

[Bierny]

Hi,
I am quite new to Python but i found it really interesting and useful so I am trying to write even the smallest tools in this language. During this passion of creating everything in Python I get stuck on the following problem.

I want to create a simple class that will be used as an interface to some application. The class shall start the application as a separate thread and try to connect to it. So, it looks like this

class MyClass:
    
    __init__(self):
        
           self.pid = os.spawnl(os.P_NOWAIT,"some_app","some_app","param1","param2")

    # the class ends here

myApp = MyClass

os.waitpid(myApp.pid,0)
print "bye"

When I try this approach I fail and I really don't know why. If i move the os.spawn ... statement outside the class it will work and os.waitpid will wait until the process is finished.

What am I doing wrong? Is it allowed to start separate thread from the constructor of a class?

Thanks in advance for any help and hints

Best regards,

[cybervegan]

Hi,
I am quite new to Python but i found it really interesting and useful so I am trying to write even the smallest tools in this language. During this passion of creating everything in Python I get stuck on the following problem.

I want to create a simple class that will be used as an interface to some application. The class shall start the application as a separate thread and try to connect to it. So, it looks like this

class MyClass:

__init__(self):

self.pid = os.spawnl(os.P_ NOWAIT,"some_ap p","some_app"," param1","param2 ")

# the class ends here

myApp = MyClass

os.waitpid(myAp p.pid,0)
print "bye"

When I try this approach I fail and I really don't know why. If i move the os.spawn ... statement outside the class it will work and os.waitpid will wait until the process is finished.

What am I doing wrong? Is it allowed to start separate thread from the constructor of a class?

Thanks in advance for any help and hints

Best regards,

Unless it's a typo, I think you are invoking the class incorrectly. You need to say:

myApp = MyClass()

Note the "()" empty brackets after MyClass: this runs the __init__ for the class and creates a new *instance* of the class. Without this, you are trying to use the *class* object itself (which obviously doesn't work).

hth,
-cybervegan

[Bierny]

Hi,
Thanks for quick reply! I just found the cause of the problem. It was, as cybervegan has written, the type of paramters passed to the constructor. Now it works as it should!

Thanks again!

Best regards,
Bierny

[bartonc]

Hi,
Thanks for quick reply! I just found the cause of the problem. It was, as cybervegan has written, the type of paramters passed to the constructor. Now it works as it should!

Thanks again!

Best regards,
Bierny

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