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Benjamin Bandt-Horn

Mac OSX : How to burn an ISO image to a USB key - The Endless Geek - 0 views

endlessgeek.com/...burn-an-iso-image-to-a-usb-key

mac osx how to burn iso image usb key

shared by Benjamin Bandt-Horn on 09 Jan 16 - No Cached
  • Benjamin Bandt-Horn on 09 Jan 16
     
    If you have tried to create a bootable USB key from an iso image in Mac OSX using Disk Utility then you have probably encountered the frustrating and almost Windows-like cryptic error message "Could not validate source - Invalid argument" error. Looking in the system log via the Console app I suspect this is because internally DiskUtil tries to run /usr/sbin/asr to verify the image, which fails.   1 2 3 $ asr imagescan --source ubuntu-rescue-remix-12-04.iso only UDIF and NDIF images can be scanned. asr: image scan failed - Invalid argument. UDIF and NDIF are image formats used by Apple, and Disk Utility is pretty hopeless with anything that falls outside of these standards. The iso standard is short for ISO9660 and is a standard that defines the format of an image intended for burning to CD. Even after using hdutil to convert the image to UDRO (a UDIF Read-Only image) Disk Utility will still stubbornly refuse to help. Disk Destroyer Duplicator to the rescue Being Unix based, OSX has the command line dd utility available. Short for Disk Duplicator, dd is a block level reader/writer that makes raw copies from one file to another. But you want to copy the image to a device, right? That's fine, because everything in the world of Unix/Linux is a file - even devices. Informally referred to as Disk Destroyer, should you tell dd to output to the wrong device then your day is definitely going to be spoiled, so to avoid any mishaps we will make sure we know which devices on your system is your USB stick. You can determine this from the command line:
Benjamin Bandt-Horn

How does polymorphism work in Python? - Stack Overflow - 0 views

stackoverflow.com/...es-polymorphism-work-in-python

python polymorphism duck-typing

shared by Benjamin Bandt-Horn on 12 Jan 14 - No Cached
  • idiomatic Python dictates that you (almost) never do type-checking, but instead rely on duck-typing for polymorphic behavior. There's nothing wrong with using isinstance to understand inheritance, but it should generally be avoided in "production" code
  • Benjamin Bandt-Horn on 12 Jan 14
     
    idiomatic Python dictates that you (almost) never do type-checking, but instead rely on duck-typing for polymorphic behavior. There's nothing wrong with using isinstance to understand inheritance, but it should generally be avoided in "production" code
Benjamin Bandt-Horn

Python: How do I pass a variable by reference? - Stack Overflow - 0 views

stackoverflow.com/...i-pass-a-variable-by-reference

python reference variables value

shared by Benjamin Bandt-Horn on 27 Dec 13 - No Cached
  • Parameters are passed by value
  • some data types are mutable, but others aren't
  • If you pass a mutable object into a method, the method gets a reference to that same object and you can mutate it to your heart's delight, but if you rebind the reference in the method, the outer scope will know nothing about it, and after you're done, the outer reference will still point at the original object.
  • ...5 more annotations...
  • List - a mutable type
  • String - an immutable type
  • you could return the new value. This doesn't change the way things are passed in, but does let you get the information you want back out:
  • use_a_wrapper_to_simulate_pass_by_reference
  • But sometimes the thing was a pointer
  • Benjamin Bandt-Horn on 27 Dec 13
     
    Parameters are passed by value
Benjamin Bandt-Horn

How to implement __iter__(self) for a container object (Python) - Stack Overflow - 0 views

stackoverflow.com/...-for-a-container-object-python

container python iterator generator List Comprehensions

shared by Benjamin Bandt-Horn on 30 Dec 13 - No Cached
  • usually __iter__() just return self if you have already define the next() method (generator object)
  • While you are looking at the collections module, consider inheriting from Sequence, Mapping or another abstract base class if that is more appropriate. Here is an example for a Sequence subclass:
  • if hasattr(self.data[0], "__iter__": return self.data[0].__iter__() return self.data.__iter__()
  • Benjamin Bandt-Horn on 30 Dec 13
     
    if not self.data: raise StopIteration
Benjamin Bandt-Horn

jcalderone: How to override comparison operators in Python - 0 views

jcalderone.livejournal.com/32837.html

comparison operators python override

shared by Benjamin Bandt-Horn on 29 Dec 13 - No Cached
  • here are the basic rules for the customization of ==, !=, <, >, <=, and >=: For all six of the above operators, if __cmp__ is defined on the left-hand argument, it is called with the right-hand argument. A result of -1 indicates the LHS is less than the RHS. A result of 0 indicates they are equal. A result of 1 indicates the LHS is greater than the RHS
  • __eq__ is not used for !=
  • For <, __lt__ is used. For >, __gt__. For <= and >=, __le__ and __ge__ respectively
  • ...1 more annotation...
  • __eq__ does an isinstance test on its argument
  • Benjamin Bandt-Horn on 29 Dec 13
     
    here are the basic rules for the customization of ==, !=, , =: For all six of the above operators, if __cmp__ is defined on the left-hand argument, it is called with the right-hand argument. A result of -1 indicates the LHS is less than the RHS. A result of 0 indicates they are equal. A result of 1 indicates the LHS is greater than the RHS.
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